# Solar Analytica — Full Content > Independent, data-driven solar intelligence — inverter fault libraries, engineering tools and plain-English technology guides. Transparency through data. This is the complete text of Solar Analytica (https://solaranalytica.com) for AI assistants: every explainer, every documented inverter fault code, all glossary terms and tool descriptions, inlined as plain text. Free to use with attribution. Last site-wide review: June 2026. For a shorter link-only map, see https://solaranalytica.com/llms.txt --- # Explainers ## AC vs DC solar panels: which is right for you? Source: https://solaranalytica.com/ac-vs-dc-solar-panels "AC" and "DC" panels really mean where the inverter lives — one per module, or one for the whole string. Here's the practical difference, and why adding a battery flips the recommendation. Key points: - Every panel produces DC; the "AC vs DC panel" label really describes where the conversion to AC happens — a microinverter on each module, or one shared string inverter for the whole array. - AC modules (microinverters) give per-panel MPPT, no single point of failure, and easier expansion, but cost more up front and put more electronics on the roof; DC modules (string inverters) are typically cheaper per watt with one inverter to service. - If a battery is on the roadmap, a DC-coupled string or hybrid inverter is usually preferable, because batteries store DC and avoid an extra AC-to-DC conversion. First, the naming Every solar panel produces direct current (DC). The "AC vs DC panel" question is really about where the conversion to AC happens. A DC module sends its DC down to a shared string inverter that converts the whole array at once. An AC module has a small microinverter attached to each panel, so it outputs grid-ready AC at the panel itself. A note on the history The distinction goes back to the 1880s "War of the Currents". Edison backed DC, which flows in one direction; Tesla and Westinghouse backed AC, whose great advantage was that transformers could easily step it up and down for efficient long-distance transmission. AC won the grid — but DC never left: it powers electronics, LEDs, EVs, batteries, and the solar cells themselves. Modern high-voltage DC (HVDC) links even carry power over long distances again. AC modules (microinverters) An AC module integrates a microinverter behind each panel, converting DC to AC on the spot. Because every panel is independent, the system behaves very differently from a single-string design. - No single point of failure. If one microinverter or panel fails, only that unit drops out — the rest keep producing. - Per-panel MPPT. Each panel runs at its own optimum, so shading or a dirty panel doesn't drag down the whole string. Mismatch losses are minimal. - Easy to expand. The minimum system is a single module, and you can add panels later without re-engineering a string. - Safer wiring. No high-voltage DC running across the roof, which reduces DC arc and fire risk. - Panel-level monitoring. You can see the output of each individual panel. The trade-offs are a higher up-front cost (you're buying many small inverters instead of one) and more electronics on the roof to maintain over the system's life. DC modules (string inverters) DC modules feed a single string (or hybrid) inverter. This is the long-standing mainstream design: typically cheaper per watt, with one accessible inverter to service. Its weaknesses are the mirror image of the AC module's strengths — a fault or heavy shading on one panel affects the string, and there's high-voltage DC cabling on the roof. Crucially, DC is what batteries store. A battery charges and discharges in DC, so DC-coupled systems (string/hybrid inverter plus battery) avoid an extra AC↔DC conversion. AC-coupled storage is possible but adds conversion steps and losses. Which is best for you? As a rule of thumb: - Panels only, complex roof or shading: AC modules (microinverters) are often the better fit — independence, per-panel MPPT, and safety outweigh the cost premium. - Planning a battery now or later: a DC-coupled string/hybrid inverter is usually preferable, because the battery and panels share DC and the inverter is already sized for storage. - Simple unshaded roof, tight budget: a string inverter is hard to beat on cost per watt. There's no universal winner — it depends on the roof, the shading, and whether storage is on the roadmap. Solar Analytica rates inverters across residential, small-commercial, and C&I tiers; see the methodology, or browse independent scores on review.solar. --- ## Microinverters vs String Inverters Source: https://solaranalytica.com/microinverters-vs-string-inverters Both convert your panels' DC into usable AC, but they do it in very different places and at very different scales. The right choice depends mostly on your roof, your shade, and your budget. Key points: - A string inverter runs one MPPT for a whole string at once, while microinverters give each panel its own inverter and MPPT so the panels work independently. - Because each panel is optimised on its own, a shaded panel only affects itself with microinverters; the benefit scales with how much and how regularly the roof is shaded, and can be modest on a lightly shaded roof. - String inverters are usually cheaper and remain the default for unshaded single-orientation roofs, while microinverters suit complex roofs, regular shade, panel-level monitoring, and later expansion. A solar inverter turns the direct current (DC) your panels generate into the alternating current (AC) your home and the grid use. The two common ways to do this are a single string inverter mounted on a wall, or many small microinverters, one fixed under each panel. This guide compares them on the things that actually change your outcome: shade, monitoring, failure behaviour, roof complexity, cost and future expansion. If the AC and DC terms are new to you, our explainer on AC vs DC solar panels covers the basics first. How each one works With a string inverter, panels are wired in series into one or more "strings", and the whole string feeds a single inverter. That inverter runs maximum power point tracking (MPPT) for the string as a unit — it finds one operating voltage that suits all the panels at once. Most household systems use one string inverter, often with two or three MPPT inputs. Microinverters flip this around. Each panel gets its own tiny inverter that runs its own MPPT and outputs AC directly. The panels work independently rather than being tied together electrically. This is a form of module-level power electronics (the other being DC optimisers paired with a string inverter). Shade tolerance and per-panel MPPT This is the headline difference. Because a string shares one MPPT channel, a single shaded, soiled or degraded panel can drag down the operating point for every panel on that string. Modern panels fit bypass diodes — usually three per panel — that route current around heavily shaded cell groups; half-cut designs keep the same three diodes but arrange them to protect six sub-strings, which improves real-world shade behaviour. Current string-inverter algorithms also handle partial shade far better than older models did. But the constraint remains: the inverter optimises the group, not the individual. Microinverters optimise each panel on its own, so a shaded panel only affects itself. In one application of the National Renewable Energy Laboratory's shading testbed, PV Evolution Labs measured a microinverter system producing 3.7% more under light shade, 7.8% more under moderate shade and 12.3% more under heavy shade than a matched string-inverter array on identical 8 kW systems. The lesson is that the benefit scales with how much, and how regularly, your roof is shaded — it is real, but for a lightly shaded roof it can be modest. Notably, Australian field testing has found that for some shade patterns a good modern string inverter can match or even slightly beat microinverters, so the advantage is situational rather than automatic. Multiple orientations and complex roofs Where panels sit on several roof faces with different tilts or directions, microinverters shine, because each panel produces to its own potential regardless of its neighbours. String systems can manage this by grouping each orientation onto its own MPPT input, but you are limited by how many inputs the inverter has. As a rule of thumb, string inverters suit simpler roofs; once you are spread across more than about three differing roof sections, microinverters become easier to design well. Orientation drives a lot of this decision — see solar panel orientation for how direction and tilt affect output. Monitoring and diagnostics String inverters report at the system (or per-string) level, so a single underperforming panel can be hard to spot. Microinverters report panel by panel, usually updating every few minutes, which makes it obvious when one module is failing, soiled or shaded. That granularity helps with fault-finding and warranty claims, at the cost of a little added system complexity. Redundancy and failure modes A string inverter is a single point of failure: if it stops, the whole system stops, and inverters often need repair or replacement within a panel set's lifetime. The trade-off is that it sits accessibly on a wall and is straightforward to swap. Microinverters distribute the risk — one failure usually means losing only that panel's output — but the units live on the roof in a hotter, harder-to-reach environment, so a fault means accessing the array. Manufacturers offset this with long warranties; some microinverters now carry warranties of up to 25 years, against around 10 years (commonly 10–12, and often extendable for a fee) for many string inverters. Cost and expandability String inverters are usually the cheaper option for a straightforward install, which is why they remain the default for unshaded, single-orientation roofs. Microinverter systems generally cost more up front. They do, however, expand cleanly: because each panel is self-contained, adding panels later is simpler than reworking string voltages to fit an existing inverter. Which suits your site Lean towards a string inverter when the roof is one or two faces, shading is minimal, and budget matters most. Lean towards microinverters when panels span several orientations, when shade is regular and unavoidable, when you want panel-level visibility, or when you expect to expand later. Whichever you choose, confirm the model is approved by the Clean Energy Council and compliant with AS/NZS 4777.2 — a non-negotiable for a safe, grid-connected Australian install. --- ## HJT solar cell technology, explained Source: https://solaranalytica.com/hjt-solar-technology Heterojunction (HJT) is one of the highest-efficiency mainstream silicon cell technologies. Here's how it works, how it compares to PERC and TOPCon, and which datasheet numbers actually matter. Key points: - An HJT cell sandwiches a crystalline-silicon wafer between two ultra-thin amorphous-silicon layers that passivate the surfaces, giving a high open-circuit voltage that underpins its efficiency advantage. - HJT typically has the best temperature coefficient of the mainstream technologies and the highest bifaciality factor, so it holds onto more rated power on hot afternoons and captures more reflected light. - Those advantages come at a cost: HJT is generally more expensive to manufacture, uses more silver, and needs careful handling because its thin amorphous layers are sensitive. What is a heterojunction (HJT) cell? An HJT cell is built around a crystalline-silicon wafer that is sandwiched between two ultra-thin layers of amorphous ("thin-film") silicon. Those amorphous layers passivate the wafer surfaces — they tie up the defects where charge carriers would otherwise be lost. The result is an exceptionally high open-circuit voltage, which is the foundation of HJT's efficiency advantage. HJT cells are naturally bifacial (they generate from both faces) and are made with a low-temperature process — typically below 200 °C — which is gentler on the wafer than the high-temperature firing steps used by other cell types. HJT vs PERC vs TOPCon PERC (Passivated Emitter and Rear Contact) is the technology HJT and TOPCon are displacing. PERC added a rear passivation layer to the older aluminium back-surface-field design, lifting cell efficiency by roughly a percentage point. TOPCon and HJT are both "next-generation" passivated-contact approaches that push higher. In practice, the differences that matter to a buyer are: - Efficiency ceiling. Mainstream PERC modules top out around 21–22%; TOPCon and HJT modules commonly reach 22–23%+ at the module level, with HJT holding the higher cell-efficiency records. - Temperature coefficient. HJT typically has the lowest (best) temperature coefficient of power — often around −0.24 to −0.26%/°C, versus roughly −0.34%/°C for PERC. Lower means less output lost as the panel heats up. - Bifaciality. HJT's bifaciality factor is the highest of the three, frequently above 90%, so it captures more reflected light on suitable mounting. - Degradation. HJT and TOPCon are largely free of the light-induced degradation (LID) that affected early PERC, so first-year and long-term degradation figures are usually better. Why HJT performs well in the real world Two properties do most of the work. The low temperature coefficient means an HJT array holds onto more of its rated power on hot afternoons — exactly when panels are hottest and, in many climates, when generation matters. The strong low-light response means it starts earlier and finishes later in the day. Combined with high bifaciality on reflective surfaces, these traits raise real-world yield relative to the nameplate rating. The trade-offs HJT is not automatically the right choice. It generally costs more to manufacture, uses more silver (and historically indium) than PERC, and demands careful handling because the thin amorphous layers are sensitive. Whether the efficiency and temperature advantages justify the price depends on roof space, climate, and budget — which is the kind of comparison our product ratings are designed to make objective. What to check on the datasheet Independent of the marketing, four numbers tell you most of what you need: - Module efficiency (%) at standard test conditions. - Temperature coefficient of Pmax (%/°C) — closer to zero is better. - Bifaciality factor (%) — only relevant if the back face will see reflected light. - Year-one and annual degradation (%), plus the performance-warranty end point. Those are four of the criteria Solar Analytica scores for every panel — see the methodology for how they're weighted. --- ## TOPCon Solar Cells, Explained Source: https://solaranalytica.com/topcon-solar-cells TOPCon is the cell architecture that has quietly replaced PERC as the mainstream of the solar market. Here is what the technology actually does, and what it means when you read a quote. Key points: - TOPCon, short for Tunnel Oxide Passivated Contact, is a refinement of the standard silicon cell built on n-type silicon, and by 2024 it had overtaken PERC as the dominant technology in new module production. - Its efficiency gain comes from a passivating contact on the rear: a roughly 1 to 2 nanometre silicon oxide layer that electrons tunnel through, paired with a doped polysilicon layer, which collects current while strongly suppressing recombination. - Because existing PERC factory lines can be upgraded to TOPCon rather than rebuilt, its manufacturing cost stayed close to PERC, which is a big part of why it scaled so fast. What TOPCon is TOPCon stands for Tunnel Oxide Passivated Contact. It is a refinement of the standard silicon solar cell rather than a wholly new device, which is one reason it spread so quickly. Where the previous mainstream design (PERC) used p-type silicon and contacted the cell directly, TOPCon is built on n-type silicon and adds a thin passivating contact on the rear of the cell. By 2024 this architecture had overtaken PERC to become the dominant technology in new module production, and industry roadmaps expect its share to keep growing for years yet. How the passivating contact works The core problem in any solar cell is recombination: charge carriers that should flow out as current are instead lost, especially where the silicon meets a metal contact. The metal is a very "leaky" surface, so direct contact wastes voltage. TOPCon tackles this with two stacked layers on the back of the cell. First comes an extremely thin layer of silicon oxide, roughly 1 to 2 nanometres thick, sitting on the silicon. On top of that sits a doped polysilicon layer that connects to the metal. The oxide is thin enough that electrons can tunnel through it (a quantum-mechanical effect), so current still flows freely. But the layer also passivates the silicon surface and is carrier-selective: it lets the wanted carriers pass while strongly suppressing recombination. The result is a contact that collects current without the heavy voltage penalty of touching bare silicon. That higher voltage is where the efficiency gain comes from. It is the same passivated-contact idea behind heterojunction cells, just achieved with a different material stack. How it compares with PERC and HJT Efficiency. Commercial TOPCon modules typically convert around 21 to 23 per cent of incoming light, a step above mainstream PERC. In the laboratory, certified TOPCon cells have reached the high 26 to 27 per cent range, edging towards the roughly 29.4 per cent practical ceiling for single-junction silicon set by Auger recombination. Heterojunction (HJT) cells sit in a similar high band; PERC is generally a percentage point or so lower at module level. Temperature coefficient. Panels lose output as they heat up. PERC modules commonly lose around 0.34 to 0.35 per cent of power per degree Celsius above the rating temperature. TOPCon is usually a little better, with many datasheets quoting around -0.29 to -0.30 per cent per degree. HJT is typically the strongest of the three on this measure. In hot Australian conditions the difference is real but modest, so it is worth checking the exact figure on the datasheet rather than assuming. Bifaciality. TOPCon cells collect light from the rear as well as the front. Their bifaciality factor (rear output as a share of front) is often quoted around 80 to 90 per cent, higher than typical PERC and useful for ground-mount and elevated installs with reflective surfaces. HJT's symmetric structure can push this higher still. Degradation and LID/LeTID. Because TOPCon uses n-type silicon, it sidesteps the boron-oxygen light-induced degradation (LID) that affects many p-type PERC products, and is generally less prone to light- and elevated-temperature-induced degradation (LeTID), though it is not wholly immune to the latter. Manufacturers commonly warrant TOPCon at around 1 per cent loss in the first year and roughly 0.4 per cent per year thereafter, often over a 30-year term. PERC warranties are usually a touch steeper; HJT is generally similar to or slightly better than TOPCon. Cost and maturity. A major practical advantage is that existing PERC factory lines can be upgraded to TOPCon with extra steps (such as the oxide and polysilicon deposition) rather than rebuilt from scratch. That kept manufacturing costs close to PERC and is a big part of why TOPCon scaled so fast. HJT uses a more distinct, lower-temperature process and has historically carried a cost premium. What it means for buyers For most Australian rooftops, TOPCon is now simply what a good mainstream panel is made of. The sensible takeaway is not to chase the cell acronym but to read the numbers it produces: rated efficiency, the temperature coefficient, the bifaciality factor (if relevant to your install), and the performance warranty's year-one and annual degradation figures. Two panels both labelled "TOPCon" can still differ meaningfully on these. If you want to understand the line items on a quote, see reading a solar datasheet; and for how TOPCon's passivated-contact cousin differs, see HJT solar technology. The headline efficiency records make good marketing, but the gap between a laboratory cell and a panel on your roof is large, and real-world output depends far more on orientation, shading, temperature and installation quality than on which high-efficiency n-type architecture you chose. --- ## Solar cell busbars and fingers, explained Source: https://solaranalytica.com/solar-cell-busbars The thin metal lines on a solar cell are a balancing act between collecting current and blocking light. Here's what busbars and fingers do, why multi-busbar designs took over, and how rear-contact and passivation enhancements fit in. Key points: - The front metal grid is a compromise: it has to carry current out of the cell while shading as little of it as possible, so cell design balances shading losses against contact resistance. - Multi-busbar layouts replaced 3 and 5 busbar designs because more, shorter current paths cut series resistance, reduce front-side silver use and shading, and improve tolerance to micro-cracks. - Rear-surface passivation families (PERC, PERT, PERL) and bifacial construction are separate from the front grid and are where much of the last decade's efficiency gains came from. The front-contact trade-off The metal grid on the front of a cell has to do two opposing things: let light into the silicon, and carry electricity out of it. Silicon is far less conductive than metal, so without a metal grid the current would have to travel too far through the cell and be lost to series resistance. But every bit of metal on the front also shades the cell. Cell design is the search for the best compromise between shading losses (which cut the current) and contact resistance (which cuts the fill factor). Three terms worth knowing - Fill factor (FF) — the ratio of the cell's maximum power to the product of its open-circuit voltage and short-circuit current. A higher fill factor means a better-performing cell. - Open-circuit voltage (Voc) — the maximum voltage the cell produces with no load connected (and therefore no current flowing). - Short-circuit current (Isc) — the current that flows when the cell's terminals are shorted (zero voltage across the cell). The rated value is quoted at standard test conditions, but Isc exists at any level of illumination. Busbars and fingers Fingers are the many fine metallisation lines that collect current across the cell surface. Busbars are the larger strips that gather current from the fingers and connect to the external leads (the ribbons that join cells together). The whole grid is laid out to minimise both resistive loss and reflection from excess metal. Why multi-busbar (MBB) won Adding more busbars gives the current more, shorter paths to reach a collector — which shortens the distance it has to travel through the resistive fingers, one of the largest contributors to a cell's series resistance (alongside the emitter, the metal–silicon contact, and the interconnect). That's why designs moved from 3 and 5 busbars (5BB) to multi-busbar layouts with nine or more thin round wires. The advantages compound: - Cuts front-side silver use — the savings vary widely by baseline, commonly cited around 10–30% per watt, and up to ~50%+ against older 3BB or full-ribbon designs. - Less metal on the front means less shading. - Round wires reflect some light back into the cell rather than straight out. - Shorter finger paths reduce resistive losses and improve tolerance to micro-cracks. - Better suited to bifacial light harvesting. Rear-contact cells Rear- (or back-) contact designs move some or all of the front grid to the back of the cell. With the front largely clear of metal, shading losses fall and cells are easier to interconnect — at the cost of more demanding manufacturing. The approach pays off most in high-current, high-efficiency cells. Passivation enhancements: PERC, PERT, PERL Separate from the front grid, the back of the cell is where the last decade of efficiency gains came from — by adding passivation layers that stop charge carriers recombining at the rear surface. PERC — Passivated Emitter and Rear Contact Invented at the University of New South Wales in the 1980s and adopted commercially from around 2012, PERC adds an insulating passivation layer to the rear surface. It lifts cell efficiency by roughly one percentage point over the older design — a meaningful system-level gain — and became the mainstream baseline. PERT — Passivated Emitter Rear Totally-diffused PERT diffuses the entire rear surface instead of using an aluminium back-surface field. It supports both monofacial and bifacial builds, is typically built on n-type silicon, and avoids the light-induced degradation that affected early PERC — at broadly comparable cost. PERL — Passivated Emitter Rear Locally-diffused PERL combines ideas from PERC and PERT: both surfaces passivated, with selective rear diffusion only at the metal contacts. The original UNSW PERL cell reached around 25% efficiency on p-type float-zone silicon — a crystalline-silicon record that stood for years. The locally-diffused rear approach also pairs naturally with n-type wafers and bifaciality for long-lived, high-efficiency modules. Bifacial cells A bifacial cell generates from both faces, capturing light reflected off the ground and surroundings onto the rear. The real-world gain depends heavily on the surface below (its albedo) and the mounting height — typically in the range of 5–20% extra yield, occasionally more over bright surfaces like white gravel or snow, and close to zero on a dark, flush-mounted roof. The trade-offs are a modest manufacturing-cost premium, heavier glass-glass construction, and the need to mount them where the back can actually see reflected light. When the back face is well-exposed, glass-glass bifacial modules also tend to carry longer (often 30-year) performance warranties and resist potential-induced degradation. Whether that premium is worth it for a given roof is exactly the kind of question independent ratings should answer — see how we score build and cell technology in the methodology. --- ## Bifacial Solar Panels, Explained Source: https://solaranalytica.com/bifacial-solar-panels Bifacial modules generate from both faces, but the extra yield depends heavily on what sits beneath them. Here is how the rear side actually works, and where the gains are real rather than marketing. Key points: - A bifacial panel swaps the opaque backsheet for a transparent rear surface so the cells can also collect reflected light that has bounced off the ground back up to the underside of the array. - Albedo, the fraction of light a surface reflects, is the single biggest installation-side lever on bifacial gain; rear-side energy rises roughly in step with how reflective the ground beneath the array is. - Bifacial earns its keep on elevated, well-spaced ground mounts and tilted or raised rooftop structures over reflective ground; on a standard flush rooftop the rear sees little light, so the gain is usually small. What a bifacial panel actually is A conventional solar panel collects light on its front face only. The rear is covered by an opaque, usually white, polymer backsheet. A bifacial panel replaces that backsheet with a transparent rear surface, normally a second sheet of glass, so the cells can also collect light that reaches them from behind. That rear light is almost entirely reflected light: sunlight that has bounced off the ground or surrounding surfaces and travelled back up to the underside of the array. The idea is straightforward, but the extra energy is not free or guaranteed. It depends on the cell itself, on how much light the ground returns, and on how the array is mounted. Each of these can be measured, which is why bifacial performance is more predictable than it first appears. Bifaciality factor The first number to understand is the bifaciality factor: the ratio of the rear-side efficiency to the front-side efficiency under the same standard test conditions. A bifaciality factor of 0.80 means that, for equal light landing on each face, the rear produces 80 per cent as much power as the front. It is a property of the cell, not the installation, and it appears on the datasheet alongside the usual front-side ratings. Bifaciality depends strongly on cell architecture. Older p-type PERC cells, adapted for bifacial use, sit around 0.70. Modern n-type cells do better: TOPCon is typically in the low to mid 0.80s, while heterojunction (HJT) cells, which are inherently close to symmetric, are usually quoted in the high 0.80s to about 0.95. If you are comparing modules, the bifaciality figure tells you how much the rear can contribute before any site factors are considered. For more on how these figures are presented, see reading a solar datasheet. Albedo: the most important site variable Albedo is the fraction of light a surface reflects, from 0 (fully absorbing) to 1 (fully reflecting). It governs how much light ever reaches the rear of the panel, and it is the single biggest installation-side lever on bifacial gain. Typical values vary widely: dark soil and asphalt sit around 0.10–0.17, grass around 0.20–0.25, dry sand around 0.30–0.40, concrete anywhere from about 0.25 to 0.55 depending on age and finish, and fresh snow as high as 0.80–0.90. The relationship is close to proportional: across the usual range, rear-side energy rises roughly in step with albedo, so a brighter surface beneath the array returns markedly more light to the rear. This is why ground-mount operators sometimes lay light gravel or reflective fabric beneath rows, and why the same panel can perform very differently on a dark roof versus a pale concrete yard. Mounting height and ground cover ratio Two geometric factors decide how much of that reflected light actually lands on the rear. The first is height above the ground: panels mounted higher can "see" a wider patch of illuminated ground, and the rear receives more even, less shaded light. Field studies show rear irradiance rising noticeably as clearance increases from roughly half a metre to one or two metres, with gains levelling off beyond about 1.5 metres while structural cost keeps climbing. The second is the ground cover ratio (GCR), the proportion of land area covered by panels. Tightly packed rows shade the ground between them and shade each other's undersides, suppressing rear gain. Spacing rows further apart raises the reflected light reaching each rear face, at the cost of needing more land. Both factors favour open, elevated arrays. Realistic bifacial gain "Bifacial gain" is the extra annual energy a bifacial system produces compared with an identical monofacial one. The honest ranges are wide and site-dependent. The US National Renewable Energy Laboratory measured roughly 7 per cent for fixed-tilt ground-mount over natural ground cover, and reports that such systems generally stay under 10 per cent unless the ground is made more reflective; the broader literature spans roughly 5 per cent to 30 per cent at the favourable end, over very high-albedo ground such as snow or bright gravel with well-elevated, widely spaced rows. Typical rooftops are a different story. Most residential panels are fixed close to the roof, often little more than 10 centimetres of clearance, so very little light can reach the rear. On a dark roof the realistic gain is often just a couple of per cent; even a pale roof returns modestly at that height. Australian modelling reflects this spread: an Australian National University study found gains ranging from about 5 per cent to 23 per cent depending on tilt and roof reflectivity, but the upper figures assume tilt frames or elevated mounting with a bright surface beneath, not a flush dark roof. The practical conclusion for most homes is that bifacial helps most on flat roofs with tilt frames, carports, pergolas and ground mounts, where the rear can actually see reflected light. Construction and durability Because the rear must be transparent, bifacial modules are almost always glass-glass: tempered glass front and back rather than glass-and-backsheet. This construction tends to resist moisture ingress and ultraviolet degradation better than polymer backsheets, and many such modules carry slightly lower stated annual degradation and longer warranties. The trade-off is added weight, which matters more on rooftops than on the ground. Where it makes sense Bifacial technology earns its keep where the rear can be fed: elevated, well-spaced ground-mount arrays over reflective ground, and tilted or raised rooftop structures. On a standard flush rooftop the gain is usually small, and the decision often comes down to whether the glass-glass durability and price are competitive in their own right, rather than to the bifacial bonus. --- ## How to read a solar panel datasheet Source: https://solaranalytica.com/reading-a-solar-datasheet The datasheet is the one document that doesn't do marketing's job for it. Here are the spec lines that actually decide a panel's quality — and the ones manufacturers quietly hope you skip. Key points: - Headline electrical figures are quoted at Standard Test Conditions, a lab bench rather than your roof, so every "rated" number should be read alongside the conditions and the power tolerance behind it. - A panel's temperature coefficient of Pmax is the real-world tax: panels run far hotter than 25 degrees on a roof, and a coefficient closer to zero loses less power as the cells heat up. - "25-year warranty" covers two separate things — a product (workmanship) warranty and a performance (power) warranty — that need not be the same length, and the end-of-warranty percentage is the real promise. Every claim a salesperson makes should trace back to the datasheet. It's the manufacturer's own technical declaration — and it's exactly what Solar Analytica scores from, because it's reproducible and hard to spin. Learn to read it and you can cut through almost any pitch. The electrical specs (and the conditions behind them) The headline figures are quoted at Standard Test Conditions (STC): 1000 W/m² irradiance, 25 °C cell temperature, and an air-mass of 1.5. That's a lab bench, not your roof — keep it in mind for every "rated" number. - Rated power (Pmax, in W or Wp) — the maximum power at STC. The headline number, but only meaningful alongside the conditions and tolerance below. - Power tolerance — how far an individual panel may vary from its rating. Look for a positive-only tolerance (e.g. 0/+5 W): it guarantees you never get less than the label. A ± tolerance means some panels ship under-rated. - Module efficiency (%) — power per unit area; see our power-density calculator. Higher means more power from the same roof. - Voc, Isc, Vmp, Imp — open-circuit voltage, short-circuit current, and the voltage/current at the maximum-power point. Your installer uses these to size strings so the array stays within the inverter's window across temperature extremes. Temperature coefficients — the real-world tax Panels lose power as they heat up, and on a roof they run far hotter than 25 °C. Two things on the datasheet tell you how much that costs you: - Temperature coefficient of Pmax (%/°C) — how much power is lost per degree above 25 °C. It's negative; closer to zero is better. Around −0.34%/°C is typical for older PERC, ~−0.30%/°C for TOPCon, and −0.24 to −0.27%/°C for HJT. As a rough illustration: where the cells reach ~65 °C, a −0.34%/°C panel gives up about 13.6% (40 °C × 0.34%) before any other loss — an indicative cell-temperature estimate, not a guaranteed figure. - Temperature coefficient of Voc (%/°C) — easy to overlook but critical for design. Voltage rises as cells get colder, so on a frosty morning Voc can climb above its rated value. This is the coefficient your installer uses to ensure a cold-weather string never exceeds the inverter's — and the system's — maximum voltage. - NMOT / NOCT specs — many datasheets also list power at Nominal Module (or Operating Cell) Temperature: measured at 800 W/m² irradiance (with 20 °C ambient and 1 m/s wind), which drives the module to roughly 42–45 °C. NMOT (the newer IEC 61215:2016 term) and the older NOCT are near-equivalent but defined slightly differently, so a datasheet may show one or the other. Either way, these figures sit below STC and much closer to real operation — the more honest day-to-day expectation. The two warranties — don't conflate them "25-year warranty" is the most-abused phrase in solar. There are two separate warranties, and they're not the same length on every product: - Product (workmanship) warranty — covers manufacturing defects in the panel itself. This is the one that matters most for reliability; strong brands offer 25–30 years, weaker ones 10–15. - Performance (power) warranty — guarantees the panel still produces a minimum percentage of its rated power after a given time, despite degradation. Degradation, in the fine print - Year-one degradation — the initial drop (often ~1–2%, lower for better panels and LID-free cell types like TOPCon/HJT). - Annual degradation — the ongoing rate thereafter (e.g. ~0.4–0.55%/yr). - End-of-warranty guarantee — the floor, e.g. "≥87.4% at year 25." Two panels both called "25-year" can guarantee very different end points. - The catch — read whether claims are settled pro-rata or by replacement, and whether labour and shipping are covered. A long warranty that excludes the cost of sending a technician up a roof is worth far less than it looks. Mechanical & build specs - Cell technology — PERC, TOPCon, or HJT (see our HJT explainer and busbars guide). - Bifaciality factor (%) — only relevant if the rear face will see reflected light. - Frame, glass, junction-box IP rating — build quality indicators; IP67/IP68 on the junction box, anodised aluminium frame, and (for glass-glass) tempered front and back. - Max system voltage, max series fuse — electrical limits for array design. - Mechanical load rating — front (snow/down) and rear (wind/uplift) pressure the panel is certified to, in Pa. - Operating temperature range & environmental ratings — usually −40 to +85 °C, plus hail-impact resistance (hailstone diameter and velocity) and, where relevant, salt-mist, ammonia, and PID resistance. - Connector type & dimensions/weight — MC4-compatible connectors, and the physical size that drives the layout and handling. Certifications — and one that isn't a certification Genuine quality and safety marks to look for: - IEC 61215 — design qualification and type approval (the panel survives defined stress tests). - IEC 61730 — photovoltaic module safety qualification, which includes the module's fire class/rating (often also given as a UL 790 Class A–C rating) — needed for code compliance and insurance in many areas. - Regional listing — e.g. listing with the relevant market's approved-products scheme. "Tier 1" is not a quality or safety certification. It's a bankability ranking (originally from Bloomberg NEF) reflecting how readily large projects get financed for that maker — a measure of the manufacturer's balance sheet, not your panel's performance. Treat it as a footnote, not a verdict. (We cover this distinction in depth separately.) The lines they hope you skip - STC only, no NMOT — quoting only the optimistic lab number. - Hidden or ± power tolerance — if it isn't positive-only, ask why. - "Up to" efficiency — that's the best variant in the family, not necessarily the one you're quoted. - Wrong variant — one datasheet covers a whole power-class family; confirm the exact model number on your quote matches the column you're reading. - Warranty length without the degradation curve — the end-of-warranty percentage is the real promise. - Labour/shipping exclusions — buried in the warranty terms, not the spec table. How we use the datasheet Everything above is exactly why Solar Analytica scores only from manufacturer datasheets, against a fixed rubric — efficiency, temperature coefficient, the two warranties, degradation, cell technology, and build all carry defined weights. It makes scores reproducible and resistant to spin. Read the full approach in the methodology, or see how real products land on review.solar. --- ## Solar panel orientation: north vs east/west Source: https://solaranalytica.com/solar-panel-orientation The "best" orientation isn't the one that makes the most power — it's the one that makes power when you use it. Here's how north, east/west, and tilt trade off, in an Australian context. Key points: - In the southern hemisphere, north-facing panels produce the most total energy with a midday peak, while an east/west split produces a little less overall but spreads generation into the morning and late afternoon. - For a household out from roughly 9 to 5 with no battery, east/west can save more money because it shifts generation to the hours you are home, and self-consumed solar is worth far more than exported solar. - A battery largely dissolves the trade-off by capturing a north array's midday surplus for evening use, so if storage is in your plans, north or north-biased usually makes the most sense. Two different goals Orientation answers a question that depends entirely on what you're optimising for: maximum total generation, or maximum self-consumption. In the southern hemisphere these point in different directions — literally. - North-facing panels produce the most total energy over a year, peaking around midday when the sun is highest. - East/west-split panels produce a little less overall, but spread that generation into the morning and late afternoon. Which is better depends on when your household actually uses power — and on whether you have a battery. The case for north If your goal is the largest possible solar yield — because you have a battery to soak up the midday surplus, or a feed-in tariff that pays well, or daytime consumption (someone home, or a pool/aircon running midday) — north wins. It delivers the highest annual kWh from the same number of panels. The case for east/west For a typical household that's out from roughly 9–5 with no battery, a north array generates its peak exactly when no one is home to use it — so much of it is exported for a low feed-in rate, while the expensive evening grid power is bought back. An east/west split shifts generation toward the morning routine and the evening peak, raising the share of solar you actually use rather than export. It produces modestly less total energy but can save more money, because self-consumed solar is worth far more than exported solar. The legacy version of this article framed it as "21 reasons" tied to daily routines — coffee and toast in the morning, aircon and cooking in the evening. The underlying logic is sound: match generation to the hours you draw power. What a battery changes A battery largely dissolves the trade-off. With storage, a north array's midday surplus is captured and used in the evening, so you get both the higher total generation and high self-consumption. If storage is in your plans, north (or north-biased) usually makes the most sense. Don't forget tilt — and inverter sizing - Tilt. A tilt roughly equal to your latitude maximises annual yield; lower tilts favour summer, higher tilts favour winter. Most pitched roofs are close enough that re-tilting rarely pays off. - Oversizing the array. Within the rules your inverter and network allow, a larger array on an east/west split widens the "useful" production window and flattens the curve — often more valuable than chasing peak midday output. - Prioritise usable kilowatt-hours. The headline that matters is how many of your kWh you self-consume, not the system's theoretical peak. Orientation is a system-design choice rather than a product one — but the panels and inverter you choose still set the ceiling. Browse independent scores on review.solar, or see how we rate them in the methodology. --- ## LFP vs NMC: Home Battery Chemistry Source: https://solaranalytica.com/lfp-vs-nmc-home-batteries Most home batteries are lithium-ion, but not all lithium-ion cells are the same. The choice between LFP and NMC chemistry shapes a battery's safety, lifespan, size, and cost. Key points: - LFP and NMC are both lithium-ion, differing only in the cathode material, but that single difference cascades into almost every property a homeowner cares about. - NMC packs more energy into a smaller, lighter package, but that density advantage matters far less for a fixed home installation than it does for electric vehicles. - LFP's iron-phosphate cathode is far more thermally stable, so a damaged or faulty cell is much less likely to enter thermal runaway — the chemistry's biggest practical advantage inside a home. Two chemistries, one job Almost every home battery sold in Australia is a lithium-ion battery, but the term covers several different cell chemistries. Two dominate the residential market. The first is lithium iron phosphate, written as LFP or LiFePO4, which uses an iron-phosphate cathode. The second is nickel manganese cobalt oxide, written as NMC (sometimes NCM), which uses a layered cathode of those three metals. Both store and release energy by shuttling lithium ions between electrodes; the difference lies in the cathode material, and that single difference cascades into almost every property a homeowner cares about. Energy density and physical size Energy density describes how much energy a cell stores per unit of weight or volume. NMC has the clear advantage here. Its layered structure and higher nominal cell voltage (around 3.6–3.7 volts, against roughly 3.2 volts for LFP) let it pack more energy into a smaller, lighter package. Comparative figures put typical NMC cell energy density well above that of LFP — broadly in the order of 180–250 watt-hours per kilogram for NMC against roughly 120–180 for LFP — which is why NMC has long been favoured for electric vehicles and other uses where space and weight are tightly constrained. For a wall-mounted or floor-standing home battery, this matters far less. A few extra kilograms or centimetres rarely changes a fixed installation, so the density penalty of LFP is mostly cosmetic in a residential setting. Cycle life and depth of discharge Cycle life is where LFP pulls ahead. A cycle is one full charge and discharge, and a home battery may complete one or more each day for a decade or more. LFP cells generally tolerate more cycles before their capacity fades meaningfully, and they handle deep daily discharge well, which suits the typical solar-storage pattern of charging through the day and discharging each evening. NMC cells are durable but tend to be specified for fewer deep cycles at an equivalent depth of discharge. Manufacturers state usable capacity and warranty terms differently, so always compare the warranted throughput (often given in cycles or megawatt-hours) rather than headline numbers. Thermal stability and safety This is the most important practical difference. The iron-phosphate cathode in LFP is held together by strong phosphorus-oxygen bonds that resist breaking down when heated, so the cell is far less likely to release oxygen and enter thermal runaway (a self-sustaining overheating reaction). NMC cathodes are less thermally stable, and that tendency generally increases as the nickel content rises. A peer-reviewed study comparing cell chemistries ranked thermal-runaway danger as LCO > NCA > NCM811 >> LFP, with LFP both reaching far lower peak temperatures and releasing heat much more slowly during abuse testing. In that work the LFP cells peaked at around 240°C, against roughly 460–550°C for the nickel- and cobalt-rich chemistries, a temperature low enough that the cell did not ignite. In plain terms, an LFP cell that is damaged or faulty is much less likely to catch fire, and any event is generally less severe. Both chemistries can be safe when properly engineered, installed, and managed by a battery management system, but LFP's chemistry provides an extra margin that is valuable inside a home. Temperature behaviour Lithium-ion cells of any chemistry lose performance in the cold, as the electrolyte thickens and ions move more slowly. NMC tends to retain a little more usable capacity in very cold conditions, which is one reason it remains popular for cold-climate electric vehicles. LFP, in turn, copes well with sustained warmth. In most populated parts of Australia, where extreme cold is uncommon, neither chemistry's temperature quirks are decisive, though batteries should still be sited out of direct sun and harsh heat. Cost LFP avoids cobalt and nickel, two relatively expensive and supply-constrained metals, which has helped drive its cell cost below that of NMC at scale. Falling LFP cell prices are a major reason the chemistry has spread so quickly into stationary storage. Final installed prices depend on the whole system and the installer, not the cells alone, so treat chemistry as one input among many. Why most new home batteries are LFP The International Energy Agency notes that energy density is far less critical for stationary storage than for vehicles, and that lower cost, longer life, and lower flammability have driven a strong shift to LFP. The agency reports that LFP made up around 80 per cent of new battery-storage capacity in 2023, and that share has continued to grow. NMC still appears in some home products, particularly compact or older designs, but the trend across new residential storage is firmly towards LFP. For a buyer, the takeaway is straightforward. Confirm the chemistry, check that the product appears on the Clean Energy Council approved battery list and meets the relevant Australian safety standards, and compare warranties on a like-for-like basis. To understand the broader system context, see how storage interacts with panels in AC vs DC solar, and use the solar system size calculator to estimate the capacity your home is likely to need. --- ## Solar Export Limiting, Explained Source: https://solaranalytica.com/solar-export-limiting Most Australian rooftop systems are allowed to push only so much power back to the grid. Here is what that cap is, why your network sets it, and how the newer flexible schemes change the picture. Key points: - An export limit caps only the surplus power your system sends back to the grid, not what your home consumes on site, and is set separately from how large a system you are allowed to install. - Your DNSP, the company that owns the poles and wires, sets the cap to keep network voltages within safe limits and to defer expensive upgrades, so limits vary by region, street and transformer. - Under a tight export cap, more of a system's value comes from self-consumption and storage than from exports, so model your real daytime usage against your specific cap rather than chasing a headline size. What an export limit actually is An export limit is a cap on how much power your solar system is allowed to send back into the grid at any moment. It is measured in kilowatts (kW), and it applies only to the surplus you are exporting, not to the power your home or business consumes on site. A system can generate well above its export cap; the limit only governs what crosses the meter in the outbound direction. This is a separate question from how large a system you are permitted to install. A network may approve, say, a 10 kW inverter while still restricting exports to a much lower figure. The two numbers are set independently, which is one of the most common points of confusion for owners reading their connection approval. Why networks apply them The cap is set by your Distribution Network Service Provider (DNSP) — the company that owns the poles and wires in your area, not your electricity retailer. DNSPs apply export limits for two practical reasons. First, the low-voltage network was built to deliver power to homes, not to absorb large volumes flowing the other way. When many systems export at once on a mild, sunny day with low local demand, voltages can rise beyond safe limits and equipment can be stressed. Second, limiting exports defers expensive network upgrades that would otherwise be needed to host more rooftop solar. Because each DNSP manages a different network with different constraints, export limits vary by region and even by individual street or transformer. Figures commonly discussed in the industry sit in the single-digit kilowatts per phase, but these are not universal — the only authoritative number is the one in your own connection approval. Treat any single quoted limit with caution. Fixed and zero export limits The traditional approach is a fixed export limit: a constant cap that never changes. Your inverter is configured to hold exports at or below that figure regardless of network conditions. It is simple and predictable, but blunt — it restricts your exports even at times when the network has plenty of spare capacity to absorb them. A zero export limit is the strictest version: the system may generate and supply on-site loads but must not feed anything back to the grid. Networks impose this where the local network is already heavily loaded with solar. Zero-export sites need export-control equipment that actively monitors the connection point and winds the inverter back the instant any surplus would flow outward. How inverters enforce the limit Compliant inverters in Australia must meet AS/NZS 4777.2, the standard that governs how inverters connect to the grid, including how they respond to export and demand-response controls. Enforcing an export limit generally relies on a measurement device — typically a meter or current sensor at the connection point — that continuously reports the net flow. When outbound power approaches the cap, the inverter throttles its output (or charges a battery, if present) so the limit is never breached. This works because solar output is easy to curtail. Reducing exports does not waste anything you were already using; it simply caps the surplus. The trade-off is that any generation you could have exported above the cap, but did not consume on site, is lost. Dynamic and flexible exports The newer approach replaces a single fixed number with a limit that changes through the day. Under dynamic exports (also called flexible exports or dynamic operating envelopes), the DNSP sends a time-varying export setpoint to your site, lifting it when the network has headroom and lowering it — sometimes close to zero — during congestion. The aim is to let you export more overall than a conservative fixed cap would allow, while still protecting the network at the few times it is genuinely constrained. This requires two-way communication. South Australia's statewide rollout, building on an ARENA-supported trial, uses the CSIP-AUS profile (based on the IEEE 2030.5 protocol) so the network can talk to a compliant inverter or gateway over the internet. In that scheme, exports can rise to a higher ceiling when capacity allows and fall back to a small safety figure during congestion or if the internet connection drops. Several states and networks are at different stages of adopting similar schemes, so availability, ceilings and fallback behaviour differ across the country. How limits shape sizing and self-consumption Export limiting changes the economics of system design. If your exports are tightly capped, the value of every additional panel comes increasingly from what you use yourself rather than what you sell. That shifts the emphasis toward self-consumption: running appliances, hot water and EV charging during daylight, and adding battery storage to soak up surplus that would otherwise be curtailed. It also affects how you weigh inverter and array size. A larger array behind a low export cap can still pay off if your daytime loads are high or you store the excess, but the surplus you are forced to throw away grows. Modelling realistic daytime usage against your specific cap matters more than chasing a headline system size. Our solar system size calculator and payback calculator can help you test these trade-offs before committing. The practical takeaway Export limits are a network-management tool, not a penalty, and they are becoming more sophisticated rather than going away. Before sizing a system, confirm the export arrangement that applies at your address — fixed, zero, or dynamic — directly from your DNSP or installer, since it is location-specific. Then design around how much of your own generation you can realistically use or store, because under any export limit that is where most of the remaining value sits. --- ## Virtual Power Plants (VPP), Explained Source: https://solaranalytica.com/virtual-power-plants A virtual power plant pools thousands of home batteries and runs them as one coordinated fleet. Here is how that works in Australia, and what signing up actually means for your battery. Key points: - A VPP is not hardware but a fleet of home solar, batteries and controllable loads coordinated through software so that many small assets behave, to the market, like one large power station. - An aggregated battery fleet earns revenue by selling grid services such as frequency control, peak and network support, and wholesale arbitrage, often providing more than one at once in what the industry calls value stacking. - Joining a VPP trades some control and extra battery cycling for a stream of value, so the arithmetic is household-specific: weigh capacity committed, reserve kept, cycling depth and frequency, lock-in, and any warranty impact. What a virtual power plant actually is A virtual power plant, or VPP, is not a building or a piece of hardware. The Australian Energy Market Operator (AEMO) describes it as a group of resources coordinated through software and communications to deliver services that a conventional power station would normally provide. In an Australian household context, those resources are usually rooftop solar, home batteries and sometimes controllable loads such as hot-water systems or pool pumps. On their own, a single home battery is tiny by grid standards. But aggregate a few thousand of them and you have a fleet that can be charged or discharged together, on command, in seconds. That aggregated, software-controlled fleet is the "virtual" power plant: many small assets behaving, to the market, like one large one. How aggregated batteries provide grid services A VPP operator earns revenue by selling several distinct services into the electricity system. The same fleet can often provide more than one at a time, which the industry calls "value stacking". - Frequency control (FCAS). The grid runs at a target frequency, and AEMO keeps it within a narrow band around 50 hertz. When a large generator or load suddenly trips, frequency moves fast, and batteries are well suited to correcting it because they respond almost instantly. In the National Electricity Market the contingency frequency control services are split by how quickly a unit must respond — very fast (one-second), fast (six-second), slow (60-second) and delayed (five-minute) — each with a "raise" and a "lower" version. The very fast services were added in October 2023; before that there were three speed bands rather than four. AEMO's VPP demonstrations found that small battery fleets, like large grid batteries, proved highly effective at delivering these contingency services. - Peak and network support. A VPP can discharge during periods of high demand to ease pressure on the grid, and in some trials has provided localised network support such as voltage management. This is the role most people picture: many batteries exporting together when the system is stretched. - Wholesale arbitrage. Because wholesale electricity prices swing through the day, a VPP can charge batteries when prices are low and discharge them when prices spike. AEMO's trials found VPPs were capable of responding to market prices in real time, though in practice fleets tend to serve the household first and protect self-consumption before chasing market prices. What participation involves for owners Joining a VPP is a deal: you let an operator use part of your battery's capacity, and in return you receive some form of benefit. That benefit varies widely by program and changes over time, so treat any headline figure with caution. It may arrive as upfront sign-up credit, ongoing payments per event or per kilowatt-hour exported, a better feed-in rate, or eligibility for a battery rebate. Several Australian states have linked battery incentives to VPP participation, and the NSW Government, for example, runs a VPP incentive alongside its battery support — but the exact dollar values depend on the scheme, the year and your hardware, so confirm current terms directly with the provider rather than relying on advertised numbers. In exchange, you give up some control. During a grid event the operator can charge or discharge your battery on its schedule rather than yours, and self-consumption or backup-reserve settings may be temporarily overridden. Most reputable programs let you keep a reserve and cap how often and how deeply they will cycle your battery, but the degree of control you retain is exactly what you should read closely in any contract. That extra activity is the real cost to weigh. Each VPP event pushes additional energy through the battery, and more cycling contributes to wear over the cell's life. A well-designed program limits the depth and frequency of grid-driven discharge so the payments comfortably outweigh the marginal wear, but the arithmetic is genuinely household-specific. If you have low daytime usage and your battery often sits idle, VPP income can be close to free money. If you already self-consume most of your solar, the extra cycling may add wear for limited gain. Pros, cons and trade-offs The honest summary is that a VPP trades a measure of control and some battery wear for a stream of value you would not otherwise capture, while also providing a genuine public benefit by stabilising the grid and reducing the need for new peaking plant. - In favour: additional revenue or rebates, a more stable grid, and better use of a battery that would otherwise be idle for long stretches. - Against: reduced control during events, extra cycling and wear, returns that vary with how often power-system events occur, and terms that can change. The questions worth asking before signing are practical ones. How much capacity am I committing, and what reserve stays mine? How often and how deeply can the battery be cycled? Is there a minimum lock-in period? How is the benefit calculated, and can the rate change? And does joining affect my manufacturer warranty? A VPP is not inherently good or bad value — it depends on your usage pattern, your tariff and the specific terms on offer. The Australian picture VPPs in Australia are real but still modest in scale. AEMO's multi-year VPP demonstrations concluded with about 31 megawatts of aggregated capacity participating, most of it in South Australia, and that fleet had reached roughly three per cent of the contingency frequency control market. AEMO has flagged that as VPPs grow it will need better operational visibility of them, and that market rules are still adapting to large aggregations of small batteries. In other words, the technology is proven and the markets work, but participation is an evolving area rather than a finished one. For owners, the sensible approach is to understand what your battery does for you first — see our pieces on AC versus DC coupling and the solar payback calculator — and then judge whether a particular VPP offer adds to that on terms you are comfortable with. --- # Inverter & Battery Fault Libraries Documented error / alarm codes by manufacturer. Each entry: code — name: meaning (and the documented fix, where one exists). ## Huawei (SUN2000 series) — fault codes Source: https://solaranalytica.com/huawei-inverter-error-codes An independent reference compiled by Solar Analytica from publicly available Huawei inverter documentation. It lists the fault and alarm codes a Huawei residential inverter may report, what each one means, and the documented resolution steps. Safety note: anything involving DC isolators, AC switches, wiring, or opening the unit is licensed-electrician work — if in doubt, contact your installer rather than working on a live system. - 2001 — High string input voltage: Open-circuit voltage exceeds the maximum input voltage. — Fix: Contact your solar installer. Check the number of PV modules connected in series in the PV string, and ensure the string open-circuit voltage is no greater than the maximum operating voltage. Once the PV array is correctly configured, the alarm clears automatically. - 2002 — DC arc fault: The PV string power cable arcs or is in poor contact. Cause ID 1 = PV1, Cause ID 2 = PV2. — Fix: Contact your solar installer. Check whether the string cables arc or are in poor contact. - 2003 — DC arc fault: The PV string power cable arcs or is in poor contact. Cause ID 1 = PV1, Cause ID 2 = PV2. — Fix: Contact your solar installer. Check whether the string cables arc or are in poor contact. - 2011 — String reversed: The PV string is reverse-connected. Cause ID 1 = PV1, Cause ID 2 = PV2. — Fix: Contact your solar installer. Check whether the PV string is reverse-connected to the inverter. - 2012 — String current back-feed: Only a few PV modules are connected in series in the string, so its end voltage is lower than the other strings. Cause ID 1 = PV1, Cause ID 2 = PV2. — Fix: Contact your solar installer, who should check: - 2021 — AFCI check failure: The AFCI self-check fails — either the AFCI check circuit is abnormal, or the AFCI circuit is faulty. — Fix: Turn off the AC output switch and DC input switch, then turn them on again after 5 minutes. If the fault persists, contact your solar installer, dealer, or Huawei technical support. - 2031 — Phase wire short-circuit to PE: The impedance of the output phase wire is low, or it is short-circuited to PE. — Fix: Contact your solar installer. Check the impedance of the output phase wire to PE, locate the position with low impedance, and restore it. - 2032 — Grid failure: The grid is experiencing an outage, the AC circuit is disconnected, or the AC switch is off. - 2033 — Grid under-voltage: The grid voltage is below the lower threshold, or the under-voltage duration exceeds the value specified by LVRT. - 2034 — Grid over-voltage: The grid voltage is above the upper threshold, or the over-voltage duration exceeds the value specified by HVRT. - 2035 — Unbalanced grid voltage: The difference between grid phase voltages exceeds the upper threshold. - 2036 — Grid over-frequency: Grid exception: the actual grid frequency is higher than the local grid standard allows. - 2037 — Grid under-frequency: Grid exception: the actual grid frequency is lower than the local grid standard requires. - 2038 — Unstable grid frequency: Grid exception: the rate of change of grid frequency does not comply with the local grid standard. - 2039 — Output over-current: The grid voltage drops dramatically or the grid is short-circuited, so the inverter's transient output current exceeds the upper threshold and protection is triggered. - 2040 — Output DC component over-high: The DC component of the inverter output current exceeds the specified upper threshold. - 2051 — Abnormal residual current: The insulation impedance of the input side to PE decreases while the inverter is operating. - 2061 — Abnormal grounding: The N cable or ground cable is not connected. When a PV array is grounded, the inverter output is not connected to an isolation transformer. — Fix: Contact your solar installer. Power off the inverter and check: - 2062 — Low insulation resistance: The PV array is short-circuited to PE, or the array's environment is damp and insulation between the array and ground is poor. — Fix: Contact your solar installer, who should: - 2063 — Over-temperature: The inverter is installed in a poorly ventilated location, or the ambient temperature is too high. — Fix: Check the ventilation and ambient temperature at the install location. If ventilation is poor or the ambient temperature is above the upper threshold, improve airflow and heat dissipation. If both meet requirements, contact your dealer or Huawei technical support. - 2064 — Device fault: An unrecoverable fault has occurred on a circuit inside the inverter. — Fix: Turn off the AC output switch and DC input switch, then turn them on again after 5 minutes. If the fault persists, contact your dealer or Huawei technical support. - 2065 — Upgrade failed / software version mismatch: The upgrade did not complete normally. - 2066 — License expired: The privilege certificate has entered its grace period; the privileged feature will become invalid soon. - 2067 — Faulty power collector: Communication with the power meter is interrupted. — Fix: Contact your solar installer. Confirm the power meter settings match the actual model, that its communications parameters match the inverter's RS485 settings, that it is powered on, and that the RS485 cable is connected correctly. - 2068 — Battery abnormal: The battery is faulty or disconnected, or the battery circuit breaker is off while the battery is running. - 2070 — Active islanding: During a grid AC outage, the inverter proactively detects islanding. — Fix: Contact your installer. Check that the grid-connection voltage of the inverter is normal. - 2072 — Transient AC over-voltage: The inverter detects that the phase voltage exceeds the transient AC over-voltage protection threshold. - 2077 — Off-grid output overload: The off-grid output is overloaded or short-circuited. - 2080 — Abnormal PV module configuration: PV module configuration does not meet requirements, or the module output is reverse-connected or short-circuited. Cause IDs — 2: too many optimisers in a single string; 3: too few optimisers in a string, or abnormal sunlight; 5: abnormal optimiser output voltage; 6: abnormal string or parallel connection; 7: string configuration changed. — Fix: Contact your installer. Check that the total number of PV modules, the number per string, and the number of strings meet requirements, and that module output is not reverse-connected. - 2081 — Optimiser fault: The optimiser is offline or faulty. — Fix: Contact your dealer or Huawei technical support for optimiser replacement. - 2082 — Grid-tied / off-grid controller abnormal: The inverter fails to communicate with the Smart Backup Box, or an unrecoverable fault has occurred inside the Smart Backup Box. - 2085 — Built-in PID operation abnormal: The output resistance of the PV arrays to ground is low, or the system insulation resistance is low. — Fix: Check the impedance between the PV array output and ground; rectify any short circuit or insufficient insulation. Alternatively, turn off the AC output and DC input switches, wait the period stated on the device safety label, then turn the DC input and AC output switches back on. If the alarm persists, contact your dealer or Huawei technical support. - 2090 — Abnormal active power scheduling instruction: The DI input is abnormal, or inconsistent with the configuration. - 2091 — Abnormal reactive power scheduling instruction: The DI input is abnormal, or inconsistent with the configuration. - 61440 — Monitoring unit faulty: The flash memory is insufficient, or it has bad sectors. — Fix: Turn off the AC output switch and then the DC input switch. After 5 minutes, turn on the AC output switch and then the DC input switch. If the fault persists, the board may need replacing — contact your dealer or Huawei technical support. --- ## Fronius — fault codes Source: https://solaranalytica.com/fronius-error-codes An independent reference compiled by Solar Analytica from Fronius documentation and field sources. Fronius reports faults as numbered State codes on the display or in Solar.web — states 1–4 are normal start-up states, while a fault state shows a number in the hundreds. This covers the codes owners and installers see most often (Fronius defines 100+ in total, many internal/rare). The most common, State 102, is a grid issue — high network voltage — not a faulty inverter; don't let anyone sell you a new one to “fix” it. Safety note: insulation, earth, and DC-polarity faults are licensed-installer work, and for a DC over-voltage switch off the DC isolator first. - 102 — AC voltage too high: The grid voltage measured at the inverter is above the safe threshold, so it disconnects to protect itself. The single most common Fronius state. — Fix: This is almost always a network issue, not an inverter fault — your local grid voltage is running high. It self-restores when voltage drops. If it's frequent, contact your installer or network operator; Volt-Watt/protection settings may need review (see code 567), and the network may need to adjust the supply. - 103 — AC voltage too low: The grid voltage is below the inverter's acceptable range. — Fix: Usually self-restores when the grid returns to range. Check the AC connections/main switch; if it recurs, contact your installer or network operator. - 105 — AC frequency too high: The grid frequency is above the acceptable range. — Fix: Self-restores when the grid returns to normal. If frequent — common on a backup generator — contact your installer or network operator. - 106 — AC frequency too low: The grid frequency is below the acceptable range. — Fix: Self-restores when the grid returns to normal. If it recurs, contact your installer or network operator. - 107 — No AC grid / outside limits: No grid is available, or several grid parameters are out of range, so the inverter can't synchronise. — Fix: Check the AC main switch and that the grid is on. If the grid is present and it persists, have your installer check the connection and settings. - 108 — Stand-alone operation detected: The inverter detected an islanding condition (running disconnected from the grid). — Fix: Usually corrects automatically once the grid is stable. If it recurs, contact your installer. - 112 — RCMU error: An error in the residual-current monitoring unit (RCMU). — Fix: Restart the inverter. If it persists, contact your installer or a Fronius Service Partner. - 301 — Overcurrent (AC): A momentary AC over-current inside the inverter. — Fix: Usually rectified automatically. If it shows continuously, notify a Fronius Service Partner. - 302 — Overcurrent (DC): A momentary DC over-current inside the inverter. — Fix: Usually rectified automatically. If it shows continuously, notify a Fronius Service Partner. - 303 — DC module over-temperature: The DC power stage is too hot — usually blocked ventilation, high ambient temperature, or units mounted too close. — Fix: Clear the ventilation slots/heat sink, improve airflow, and keep the unit out of direct sun. If it recurs, contact your installer. - 304 — AC module over-temperature: The AC power stage is too hot — same causes as 303. — Fix: Clear the ventilation slots/heat sink, improve airflow, and keep the unit out of direct sun. If it recurs, contact your installer. - 306 · POWER LOW — PV output too low: The intermediate-circuit voltage is too low to feed in — usually just low light. — Fix: Corrects automatically as irradiance rises. If it shows in good sunlight, check the panels aren't shaded/dirty, or contact your installer. - 307 · DC LOW — DC input voltage too low: The DC input voltage is too low for grid feed-in. — Fix: Normal at sunrise and sunset. If it persists during the day, contact your installer to check the array. - 309 — DC input voltage MPPT 1 too high: The DC voltage on tracker 1 exceeds the inverter's maximum. — Fix: Switch off the DC isolator. The string likely has too many panels in series — your installer must re-check string sizing. - 311 — DC string polarity reversed: A DC string is wired with reversed polarity. — Fix: Switch off the DC isolator and have your installer correct the DC wiring polarity — don't do this on a live array. - 313 — DC input voltage MPPT 2 too high: The DC voltage on tracker 2 exceeds the inverter's maximum. — Fix: Switch off the DC isolator. The string likely has too many panels in series — your installer must re-check string sizing. - 326 · 327 — Fan error: A cooling-fan fault (fan 1 or fan 2). — Fix: Check the fan area for blockage. If the fan is faulty it needs replacement — contact your installer or a Fronius Service Partner. - 425 — No communication with power stage: The control can't communicate with the power-stage set. — Fix: Do an AC reset (toggle the breaker). If it continues, contact a Fronius Service Partner. - 436 — Board incompatibility: Functional incompatibility between PC boards (often after a component replacement). — Fix: Update the inverter firmware. If it persists, contact a Fronius Service Partner. - 443 — Intermediate-circuit voltage fault: The intermediate-circuit voltage is too low or asymmetric. — Fix: Restart once. If it persists, contact a Fronius Service Partner. - 447 — Insulation fault: An insulation fault in the inverter or PV array. — Fix: Often appears in wet weather and clears when dry. If it's continuous, have an installer check the array and cabling insulation — don't keep resetting it. - 448 — Neutral conductor not connected: The neutral wire is not connected. — Fix: This is an electrical wiring fault — have a licensed electrician or installer check the neutral connection. - 450 — Guard cannot be found: The safety guard module was not detected. — Fix: Restart once. If it persists, contact a Fronius Service Partner. - 452 — Processor communication error: A communication error between the inverter's processors. — Fix: Do an AC reset. If it shows continuously, contact a Fronius Service Partner. - 463 — Reversed AC polarity: The AC connector is inserted incorrectly or the phase is reversed. — Fix: An electrical wiring fault — have your installer or a Fronius Service Partner correct the AC connection. - 502 — Insulation error on the PV modules: An insulation fault between the array (DC+/DC−) and earth — frequently in damp or rainy weather. — Fix: If it clears when dry, moisture is getting in. An installer should check the panels, cabling, and MC4 connectors for water ingress or damage. If it persists in dry weather, it needs investigation — don't keep resetting it. - 509 — No feed-in for 24 hours: The inverter hasn't fed energy into the grid in the past 24 hours. — Fix: Check the panels aren't shaded, snow-covered, or dirty, and that there isn't another active fault. Normal for a brand-new install before commissioning. If it continues, contact your installer. - 516 — No communication with storage unit: The inverter can't communicate with the connected battery/storage unit. — Fix: Check the battery is powered on and its communication cabling is intact. If it persists, contact your installer or the battery supplier. - 517 — Power derating by temperature: The inverter is reducing output because it's too hot. — Fix: Clear the cooling openings and improve airflow; keep the unit out of direct sun. If it recurs, contact your installer. - 567 — Volt-Watt power reduction (GVDPR): Grid-Voltage-Dependent Power Reduction (Volt-Watt mode) is active — the inverter is curtailing output because the grid voltage is high. — Fix: This is required behaviour under Australian standards, not a fault — acknowledge it. If it happens often, your network voltage is high; contact your installer or network operator, as it's reducing your generation. --- ## SMA — fault codes Source: https://solaranalytica.com/sma-error-codes An independent reference compiled by Solar Analytica from SMA documentation and field sources. SMA reports faults as numbered event codes on the inverter display or in Sunny Portal / SMA 360°. This covers the common operational codes; SMA defines hundreds in total (including battery, network, and firmware-update events). Note: the insulation and residual-current events (3501, 3701) can latch on some Sunny Boy models and block restart even after the fault is fixed — once an installer has repaired the cause, they're cleared via Sunny Portal (SMA advises no more than once per day). Safety: a DC over-voltage (3401) can destroy the inverter — switch off the DC isolator and call your installer; insulation, residual-current, and earth faults are licensed-installer work. - 101 · 102 · 103 · 105 — Grid voltage / impedance too high: The grid voltage or grid impedance at the inverter's connection point is too high, so it disconnects. — Fix: Usually a network issue rather than a faulty inverter. Confirm the country dataset is correct and the grid voltage is in range; if it's frequently high, contact your installer or network operator. It self-restores when voltage returns to range. - 202 · 203 · 205 — Grid disconnected / voltage too low: The grid has been disconnected, the AC cable is damaged, or the grid voltage is too low. — Fix: Check the AC circuit breaker / main switch is on and the grid is present. If the grid is fine and it persists, have an installer inspect the AC cable and connections. - 301 — 10-minute average voltage out of range: The ten-minute average grid voltage is outside the permissible range. — Fix: Monitor the grid voltage during operation. If it's persistently out of range due to local conditions, contact your network operator. - 302 — Power reduced — high AC voltage: The inverter has reduced its output because the grid voltage is high (Volt-Watt response, to support grid stability). — Fix: Expected behaviour when grid voltage is high, not a fault. If it happens often it's costing you generation — your network voltage is high; contact your installer or network operator. - 401 · 404 — Islanding / frequency change: A stand-alone (islanded) grid or a very large change in grid frequency was detected. — Fix: Usually a short-term grid event that self-clears. If it recurs, have your installer check the grid connection for frequency fluctuations. - 501 — Grid frequency out of range: The power frequency is outside the permissible range. — Fix: Monitor the frequency. If fluctuations are frequent — common on a backup generator — contact your network operator. - 601 — Excess DC in grid current: The inverter detected an excessively high proportion of direct current in the grid current. — Fix: If it recurs, contact your installer; the grid operator may need to raise the monitoring threshold, or the inverter may need a service check. - 901 — Grounding (PE) connection missing: The protective-earth (grounding) conductor is not correctly connected. — Fix: An electrical-safety fault — have a licensed electrician or installer check the earth connection against the installation manual. Don't keep resetting it. - 1001 — Line and neutral swapped: The L (active) and N (neutral) connections are swapped. — Fix: A wiring fault — have your installer correct the L and N connections per the installation manual. - 1302 — Waiting for grid voltage: L or N is not connected (or an AC conductor is damaged) — often simply a mains outage. — Fix: If there's a power cut, it clears when supply returns. Otherwise check the AC main switch is on and the breaker hasn't tripped; if it persists, have an installer check the AC conductors. - 1501 — Reconnection fault (country dataset): A changed country dataset or parameter value doesn't match local requirements. — Fix: Your installer should verify the correct country standard is configured (the “Set country standard” parameter). - 3301 · 3302 · 3303 — Unstable operation (low DC): There isn't enough power at the DC input for stable operation. — Fix: Often just low light, shading, or snow on the array. Check the panels are clear and the array is error-free; if it persists in good sun, contact your installer. - 3401 · 3402 · 3407 — DC over-voltage: Over-voltage at the DC input — this can destroy the inverter. — Fix: Switch off the DC isolator and contact your installer immediately. The DC input voltage is above the inverter's maximum — the string is likely sized too long and must be corrected by a professional before reconnection. - 3501 — Insulation failure (ground fault): A ground fault / low insulation resistance detected on the DC (PV) side — safety-critical, and common in wet weather. — Fix: An installer must check the PV array and DC cabling for ground faults. On some Sunny Boy models this latches — after the fault is repaired it's cleared via Sunny Portal (no more than once a day). Don't keep resetting it. - 3701 — Residual current too high: The inverter detected an excessive residual (earth-leakage) current — an electric-shock hazard. — Fix: An installer must check the PV array and DC cabling for ground faults. Like 3501 it can latch and is cleared via Sunny Portal after repair (max once per day). Treat it as safety-critical. - 3801 · 3802 · 3805 — DC over-current: Over-current at the DC input; the inverter briefly interrupts feed-in. — Fix: If it's frequent, have your installer verify the PV array is correctly rated and wired (and check for a short circuit). - 3901 · 3902 — Waiting for DC start conditions: The conditions for feeding into the grid aren't yet met — typically insufficient irradiation. — Fix: Normal early/late in the day. Make sure the array isn't covered or shaded; if it persists in good sun, contact your installer. - 6501 · 6502 · 6509 — Over-temperature: The inverter has switched off (or derated) due to excessive temperature. — Fix: Clear dust from the cooling fins and air ducts, ensure good ventilation, and keep the ambient temperature within limits (and the unit out of direct sun). If it persists, contact your installer. - 6512 — Minimum operating temperature not reached: It's too cold — the inverter only resumes feed-in once the temperature reaches at least −25 °C. — Fix: No action needed; it resumes automatically as the temperature rises. - 7500 · 7501 — Fan fault: A cooling fan is not functioning properly. — Fix: Check the fan area for blockage. If the fan is faulty it needs service — contact your installer or SMA Service. - 7701 · 7702 · 7703 — Grid relay defect: The grid disconnection relay is defective or failed its test. — Fix: A hardware fault — contact SMA Service or your installer. If shown only occasionally, note whether it recurs. - 8003 — Power reduced — temperature: The inverter has reduced output for more than ten minutes because of excessive temperature. — Fix: Clean the cooling fins and air ducts, ensure adequate ventilation, and keep the ambient temperature within the rated limit. If it recurs, contact your installer. - 9002 — Grid Guard code invalid: The SMA Grid Guard code entered is incorrect, so the protected operating parameters stay locked. — Fix: An installer-level message — enter the correct SMA Grid Guard code. Not something a homeowner needs to action. - 9003 — Grid parameters locked: Changes to the grid parameters are now blocked (they require the Grid Guard code). — Fix: Informational. To change protected parameters, an installer logs in with the Grid Guard code. - 9007 — Self-test aborted: The inverter's self-test was terminated. — Fix: Check the AC connection is correct and restart the self-test. If it keeps aborting, contact your installer. --- ## Sungrow — fault codes Source: https://solaranalytica.com/sungrow-alarm-codes An independent reference compiled by Solar Analytica from publicly available Sungrow inverter documentation. It covers Sungrow string inverters, SH residential-hybrid inverters, and battery / BDC fault and alarm codes. Codes that share a single cause and remedy are grouped — every individual code number is still listed and searchable. Safety note: several Sungrow remedies involve disconnecting AC and DC switches and waiting before re-energising — anything involving wiring or opening the unit is licensed-electrician work; if in doubt, contact your installer. - 002 — Grid over-voltage: The grid voltage exceeds the protective value. — Fix: Check the grid voltage. If it exceeds the permissible range, contact the utility company; otherwise contact Sungrow or your solar installer. - 003 — Transient over-voltage: The grid transient voltage exceeds the inverter's allowable upper limit. — Fix: Wait a moment for the inverter to recover. If the fault persists, contact Sungrow or your solar installer. - 004 — Grid under-voltage: The grid voltage is below the protective value. — Fix: Check the grid voltage. If it is outside the permissible range, contact the utility company; otherwise contact Sungrow or your solar installer. - 005 — Grid under-voltage (lower threshold): The grid voltage is below the protective value — lower than the threshold for code 004. — Fix: This is a short-term fault due to grid conditions. Wait a moment for the inverter to recover. If the fault persists, contact Sungrow or your solar installer. - 006 — AC over-current: The AC output current exceeds the inverter's allowable upper limit. — Fix: The inverter resumes once the output current falls below the protection value. If the fault persists, contact Sungrow or your solar installer. - 007 — Transient AC over-current: A transient AC over-current was detected. — Fix: The inverter self-recovers after a few seconds. If the fault persists, contact Sungrow or your solar installer. - 008 — Grid over-frequency: The grid frequency exceeds the protective value. — Fix: Check the grid frequency. If it exceeds the permissible range, contact the utility company; otherwise contact Sungrow or your solar installer. - 009 — Grid under-frequency: The grid frequency is below the protective value. — Fix: Check the grid frequency. If it is outside the permissible range, contact the utility company; otherwise contact Sungrow or your solar installer. - 010 — Grid failure (islanding): A grid failure or islanding condition was detected. — Fix: Check the AC circuit breaker status, AC cable connections, and grid service status. If all are OK, contact Sungrow or your solar installer. - 011 — DC injection over-current: The DC current injected into the AC output exceeds the upper limit. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 012 — Leakage current over-current: The leakage current exceeds the inverter's allowable upper limit. — Fix: Check the PV strings for ground faults. If the fault repeats, contact Sungrow or your solar installer. - 013 — Grid abnormal: The grid voltage or frequency is outside the permissible range, so the inverter cannot connect to the grid. — Fix: The inverter generally reconnects after the grid recovers. If it occurs frequently, measure the grid parameters and contact the utility company or Sungrow. - 014 — 10-minute grid over-voltage: The average grid voltage over 10 minutes exceeds the permissible range. — Fix: Verify the country code, check the grid voltage against the permissible range, and contact the utility company if needed. - 015 — Grid over-voltage (higher threshold): The grid voltage exceeds the protective value — higher than the threshold for code 002. — Fix: Check the AC cable model and verify the grid voltage. Contact the utility company if needed, or Sungrow. - 016 — High bus voltage / power: The bus voltage or power is high. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 017 — Grid voltage unbalance: Unbalanced three-phase grid voltage was detected. — Fix: Measure the grid voltage; if it is unbalanced, contact the utility company. If it is within range, you can modify the parameter settings via the app. - 019 — Bus transient over-voltage: The transient bus voltage exceeds the inverter's allowable upper limit. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 020 — Bus over-voltage: The bus voltage exceeds the inverter's allowable upper limit. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 021 — PV1 input over-current: The PV1 input over-current limit was exceeded. — Fix: Check the PV1 input layout and wiring. Contact your solar installer. - 022 — PV2 input over-current: The PV2 input over-current limit was exceeded. — Fix: Check the PV2 input layout and wiring. Contact your solar installer. - 024 — Neutral point voltage imbalance: The deviation of the neutral point voltage exceeds the allowable limit. — Fix: The inverter recovers once the deviation falls below the protective limit. Wait a moment for recovery or restart the system. If the fault persists, contact your solar installer. - 024–025 · 030–034 · 040–042 · 050 · 060 · 076 · 116–117 — Device abnormal: An internal device abnormality was detected. (Sungrow groups these codes under a single remedy.) — Fix: Wait for the inverter to recover. Disconnect the AC and DC switches or circuit breakers, then reconnect them after 15 minutes. If the alarm persists, contact Sungrow or your solar installer. - 028 — PV1 reverse connection: PV1 is connected with reversed polarity. — Fix: Check the PV1 cable connections. Contact your solar installer. - 029 — PV2 reverse connection: PV2 is connected with reversed polarity. — Fix: Check the PV2 cable connections. Contact your solar installer. - 036 — Radiator over-temperature: The radiator (heat sink) temperature is too high. — Fix: Check the ambient temperature, ensure adequate ventilation space, avoid direct sunlight, verify the fan operates, and clean the air inlets. - 037 — Internal inverter over-temperature: The internal temperature of the inverter is too high. — Fix: Check the ambient temperature, ensure adequate ventilation space, avoid direct sunlight, verify the fan operates, and clean the air inlets. - 038 — Grid-side relay fault: A relay fault on the grid side was detected. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 039 — Low PV-to-earth insulation resistance: The insulation resistance of the PV array to earth is low. — Fix: Check the inverter grounding line and verify there are no PV string short-circuits to ground. Contact your solar installer if it persists. - 041 — Leakage current sampling fault: The leakage-current sampling circuit faulted. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 043 — Inner under-temperature fault: The ambient temperature inside the inverter is too low. — Fix: The inverter recovers once the ambient temperature rises above −25 °C. - 044 — Inverter self-test fault: The inverter self-test failed. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 045 — PV1 boost circuit fault: A fault was detected in the PV1 boost circuit. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 046 — PV2 boost circuit fault: A fault was detected in the PV2 boost circuit. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 047 — PV inputs error: The PV inputs order is incorrect. — Fix: Stop and disconnect the inverter. Contact your solar installer to reset the PV inputs order. - 048 — Phase current sampling fault: The phase-current sampling circuit faulted. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 051 — Load over-power (off-grid mode): The load power exceeds the limit in off-grid mode. — Fix: If it persists, contact your installer and disconnect non-essential loads. - 052 — INV under-voltage (off-grid mode): Inverter under-voltage fault in off-grid mode. — Fix: Wait 5 minutes for recovery, or restart the system. - 053 — Slave DSP grid over-voltage detection: The slave DSP detected that the grid voltage exceeds the inverter's allowable upper limit. — Fix: Check the grid voltage. Contact the utility company if it exceeds the range, otherwise Sungrow or your solar installer. - 054 — Slave DSP grid over-frequency detection: The slave DSP detected that the grid frequency exceeds the inverter's allowable upper limit. — Fix: Check the grid frequency. Contact the utility company if it exceeds the range, otherwise Sungrow or your solar installer. - 056 — Slave DSP leakage current detection: The slave DSP detected that the leakage current exceeds the inverter's allowable upper limit. — Fix: Check for PV string ground faults. Contact Sungrow or your solar installer if it repeats. - 059 — Master–slave DSP communication alarm: A communication alarm between the master and slave DSP. — Fix: Wait 1 minute for the inverter to recover. If the fault persists, contact Sungrow or your solar installer. - 061 — No inverter model setting: No inverter model has been set. — Fix: Contact Sungrow or your solar installer. - 062 — STB5K backup box DI fault: A DI fault of the STB5K backup box. — Fix: Check the DI connection between the inverter and the backup box. Wait 5 minutes for recovery. - 063 — CPLD version undetectable: The version of the CPLD (complex programmable logic device) cannot be detected. — Fix: Power off the system and program the CPLD. - 064 — INV over-voltage (off-grid mode): Inverter over-voltage fault in off-grid mode. — Fix: Wait 5 minutes for recovery, or restart the system. - 065 — INV under-frequency (off-grid mode): Inverter under-frequency fault in off-grid mode (default value 47 Hz). — Fix: Wait 5 minutes for recovery, or restart the system. - 066 — INV over-frequency (off-grid mode): Inverter over-frequency fault in off-grid mode (default value 52 Hz). — Fix: Wait 5 minutes for recovery, or restart the system. - 067 — Temporary grid over-voltage (off-grid mode): A temporary grid over-voltage in off-grid mode. — Fix: Wait 5 minutes for recovery, or restart the system. - 070 — Defective fans: The fans are defective (−D series only). — Fix: Stop the inverter and disconnect the cables. Check for a blocked fan duct, and replace the fans if necessary. - 071 — SPD alarm — AC: An AC surge protection device (SPD) alarm. — Fix: Check the SPD and replace it if necessary. Contact Sungrow or your solar installer. - 072 — SPD alarm — DC: A DC surge protection device (SPD) alarm. — Fix: Check the SPD and replace it if necessary. Contact Sungrow or your solar installer. - 075 — Parallel inverter RS485 communication error: An RS485 communication error between two inverters in parallel. — Fix: Check the RS485 cable connection and the parallel settings in the LCD menu. Contact Sungrow or your solar installer. - 078–079 — PV string abnormal: A PV string is abnormal. — Fix: Check whether the string needs to be connected, verify a reliable connection, and check the DC fuse status. Contact your installer if it persists. - 083 — Fan 2 abnormal speed warning: Fan 2 is running at an abnormal speed. — Fix: Check whether the fan is blocked. Restart the system. - 084 — Energy Meter reverse cable connection: The Energy Meter cable connection is reversed. — Fix: Check the power-cable polarity, verify the “Existing Inverter” setting, and check the CT clamp placement for a single-phase sensor. - 085 — Mismatched software version: The software versions do not match. — Fix: Contact Sungrow. - 087 — AFCI abnormal: The arc-fault detection (AFCI) module is abnormal. — Fix: The inverter can operate normally. Check whether the related cable connections and terminals are abnormal, and whether the ambient environment is abnormal; take corrective measures if so. If the alarm persists, contact Sungrow or your solar installer. - 088 — Arc fault: A DC arc fault was detected. — Fix: Disconnect the DC inputs and check the cables for damage, the terminal connections, the fuses, and for burnt modules. Reconnect and clear the alarm via the app. Contact your installer if it persists. - 089 — AFCI function disabled: The AFCI function is disabled. — Fix: Enable the AFCI function via the app and the inverter will recover. If the alarm persists, contact Sungrow or your solar installer. - 100 — AC output over-current: The AC output current exceeds the upper limit. — Fix: The inverter resumes once the output current falls below the protection value. If the fault persists, contact Sungrow or your solar installer. - 101 — Grid over-frequency (higher threshold): The grid frequency exceeds the protective value — higher than the threshold for code 008. — Fix: Check the grid frequency. Contact the utility company if it exceeds the range, otherwise Sungrow or your solar installer. - 102 — Grid under-frequency (lower threshold): The grid frequency is below the protective value — lower than the threshold for code 009. — Fix: Check the grid frequency. Contact the utility company if it exceeds the range, otherwise Sungrow or your solar installer. - 105 — SPI auto-test fault (Italy only): The SPI auto-test failed (Italy only). — Fix: Restart the system and re-run the auto-test if necessary. If the fault persists, contact Sungrow for a solution. - 106 — Abnormal grounding: Neither the PE terminal on the AC connection block nor the second PE terminal on the enclosure is reliably connected. — Fix: Check the inverter grounding line and the ground access. Contact Sungrow or your solar installer if it persists. - 107 — DC injection over-voltage (off-grid mode): The DC injection of the inverter voltage exceeds the upper limit, in off-grid mode. — Fix: The inverter recovers once the DC injection voltage falls below the recovery value. - 113 — Temporary bypass over-current: A temporary over-current on the bypass path. — Fix: Check the BACKUP-port load power against the upper limit. Wait for recovery or restart. Contact Sungrow if it persists. - 200 — Bus hardware over-voltage: The bus voltage exceeds the hardware protective value. — Fix: Wait for the inverter to recover once the bus voltage drops. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 201 — Bus voltage too low: The bus voltage is too low. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 202 — PV hardware over-current: The PV1 or PV2 current exceeds the hardware protective value. — Fix: Contact Sungrow or your solar installer if it repeats. - 203 — PV input voltage exceeds bus voltage: The PV input voltage exceeds the bus voltage. — Fix: Check the PV connection terminal functionality. Contact your solar installer. - 204 — PV1 boost short-circuit fault: A short-circuit fault in the PV1 boost stage. — Fix: The inverter may be damaged. Contact Sungrow for a solution. - 205 — PV2 boost short-circuit fault: A short-circuit fault in the PV2 boost stage. — Fix: The inverter may be damaged. Contact Sungrow for a solution. - 300 — INV over-temperature: Inverter over-temperature fault. — Fix: Check and clean the heat sink, verify the inverter is not in direct sunlight and the ambient temperature is below 45–60 °C, then restart. - 302 — PV insulation resistance fault: Low PV insulation resistance. — Fix: Check the PV cable connection integrity. Wait for a sunny day to test. Contact your installer if it persists. - 303 — Bypass relay fault: A fault in the bypass relay. — Fix: Wait 5 minutes for the inverter to recover, or restart the system. If the error persists, contact Sungrow or your solar installer. - 304 — Off-grid relay fault: A fault in the off-grid relay. — Fix: Wait 5 minutes for the inverter to recover, or restart the system. If the error persists, contact Sungrow or your solar installer. - 306 — Input and output power mismatch: The input and output power do not match. — Fix: Contact Sungrow or your solar installer if it repeats. - 308 — Slave DSP redundant fault: A redundancy fault on the slave DSP. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 309 — Phase voltage sampling fault: The phase-voltage sampling circuit faulted. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 312 — DC injection sampling fault: The DC-injection sampling circuit faulted. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 315 — PV1 current sampling fault: The PV1 current-sampling channel is anomalous. — Fix: Contact Sungrow or your solar installer. - 316 — PV2 current sampling fault: The PV2 current-sampling channel is anomalous. — Fix: Contact Sungrow or your solar installer. - 317 — PV1 MPPT current sampling fault: The PV1 MPPT current-sampling circuit faulted. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 318 — PV2 MPPT current sampling fault: The PV2 MPPT current-sampling circuit faulted. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 319 — System power supply failure: A failure of the system power supply. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 320 — Leakage current sensor fault: A fault in the leakage-current sensor. — Fix: Contact Sungrow or your solar installer. - 321 — SPI communication failure: Communication faults between the master DSP and the slave DSP. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 322 — Master DSP communication fault: A communication fault on the master DSP. — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 401–408 — Permanent faults: A permanent fault was recorded. (Sungrow groups these codes under a single remedy.) — Fix: Restart the system. Contact Sungrow or your solar installer if it persists. - 409 — All temperature sensors fail: All temperature sensors have failed. — Fix: Contact Sungrow or your solar installer if it repeats. - 501 — FRAM1 reading warning: An external-memory read/write warning (FRAM1). — Fix: The inverter can still connect to the grid. Restart the system. If the fault persists, contact Sungrow or your solar installer. - 503 — Ambient temp sensor open-circuit: Ambient temperature sensor open-circuit warning. — Fix: Contact Sungrow or your solar installer if it repeats. - 504 — Ambient temp sensor short-circuit: Ambient temperature sensor short-circuit warning. — Fix: Contact Sungrow or your solar installer if it repeats. - 505 — Radiator temp sensor open-circuit: Radiator temperature sensor open-circuit warning. — Fix: Contact Sungrow or your solar installer if it repeats. - 506 — Radiator temp sensor short-circuit: Radiator temperature sensor short-circuit warning. — Fix: Contact Sungrow or your solar installer if it repeats. - 507 — DO power settings error: An error in the DO (digital output) power settings. — Fix: Modify the DO control power according to the load power. See “Optimised Control” in the user manual. - 509 — Clock reset fault: The clock has been reset. — Fix: Manually reset the clock, or synchronise with network time, to clear the fault. - 510 — PV over-voltage fault: The PV voltage exceeds the permissible range. — Fix: Contact your installer to verify the PV array configuration is within the permissible range. Wait for recovery or restart. - 511 — Ambient temp sensor open-circuit: Ambient temperature sensor open-circuit warning. — Fix: Contact Sungrow or your solar installer if it repeats. - 513 — Fan 1 abnormal speed warning: Fan 1 is running at an abnormal speed. — Fix: Check whether the fan is blocked. Restart the system. - 514 — Energy Meter communication warning: Abnormal Energy Meter communication (the inverter can still connect to the grid). — Fix: Check the meter power-cable connections and the RS485 connection. Contact your installer if it persists. - 532–535 — String reverse connection: A PV string is connected with reversed polarity. — Fix: Check the string polarity; adjust only when solar radiation is low and the string current is below 0.5 A. Contact Sungrow if it persists. - 548–551 — Abnormal PV string current: A PV string current is abnormal. — Fix: Check for shaded PV modules; remove shade and clean them. Check for abnormal module aging. Contact Sungrow if it persists. - 622 — Leakage current sampling fault: The leakage-current sampling circuit faulted. — Fix: Wait a moment for the inverter to recover. If the fault occurs repeatedly, contact Sungrow or your solar installer. - 600 — Temporary BDC charging over-current: A temporary over-current during battery (BDC) charging. — Fix: Wait for the system to recover, or restart. - 601 — Temporary BDC discharging over-current: A temporary over-current during battery (BDC) discharging. — Fix: Wait for the system to recover, or restart. - 602 — Clamping capacitor under-voltage: The clamping-capacitor voltage is too low. — Fix: Check the battery cable connection. Wait for recovery or restart. - 603 — Temporary clamping capacitor over-voltage: A temporary clamping-capacitor over-voltage. — Fix: Wait for the system to recover, or restart. - 608 — BDC circuit self-check fault: The battery (BDC) circuit self-check failed. — Fix: Wait for the system to recover, or restart. - 612 — BDC over-temperature: The battery (BDC) stage is over temperature. — Fix: Check and clean the heat sink, verify the location is not in sunlight and the ambient temperature is below 45 °C, then restart. - 616 — BDC hardware over-current: The battery (BDC) hardware over-current limit was exceeded. — Fix: The system resumes once the battery charge/discharge current falls below the upper limit, or restart the system. - 620 — BDC current sampling fault: The battery (BDC) current-sampling circuit faulted. — Fix: Wait for the system to recover, or restart. - 623 — Slave DSP communication fault: A slave DSP communication fault. — Fix: Wait for the system to recover, or restart. - 624 — BDC soft-start fault: The battery (BDC) soft-start failed. — Fix: Wait for the system to recover, or restart. - 703 — Battery average under-voltage: The average battery voltage is too low. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 707 — Battery over-temperature: The battery is over temperature. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery's ambient temperature. Wait for recovery or restart. - 708 — Battery under-temperature: The battery is under temperature. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery's ambient temperature. Wait for recovery or restart. - 711 — Instantaneous battery over-voltage: An instantaneous battery over-voltage. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 712 — Battery average over-voltage: The average battery voltage is too high. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 714 — Abnormal battery–inverter communication: Abnormal communication between the battery and the hybrid inverter. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery type and communication connection; set the battery type for lead-acid if applicable. Restart if needed. - 715 — Battery hardware over-voltage: The battery hardware over-voltage limit was exceeded. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 732 — Battery over-voltage protection: Battery over-voltage protection has triggered. — Fix: The inverter stays grid-connected. Charging has stopped but discharging is allowed. Wait a moment for recovery. - 733 — Battery over-temperature protection: Battery over-temperature protection has triggered. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery's ambient temperature. Wait for recovery or restart. - 734 — Battery under-temperature protection: Battery under-temperature protection has triggered. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery's ambient temperature. Wait for recovery or restart. - 735 — Battery charge/discharge over-current protection: Battery charging/discharging over-current protection has triggered. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 739 — Battery under-voltage protection: Battery under-voltage protection has triggered. — Fix: The inverter stays grid-connected. Discharging has stopped but charging is allowed. Wait a moment for recovery. - 800 · 802 · 804 · 807 — BDC internal permanent fault: An internal permanent fault in the battery (BDC) stage. (Sungrow groups these codes under a single remedy.) — Fix: Restart the system. Contact Sungrow if it persists. - 832 — Battery FET fault: A battery FET fault or electrical switch failure. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery port voltage and cable connection. Force-shutdown and restart the system. - 834 — Battery over-current permanent fault: A battery charging/discharging over-current permanent fault. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery port voltage and cable connection. Force-shutdown and restart the system. - 836 — ID competing failure: An ID-competing failure. — Fix: Restart the system. Contact Sungrow if it persists. - 839 — Mismatched software version: The software versions do not match. — Fix: Contact Sungrow for a solution. - 844 — Software self-verifying failure: The software self-verification failed. — Fix: Restart the system. Contact Sungrow if it persists. - 864 — Battery cell over-voltage: A battery cell over-voltage fault. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 866 — Battery pre-charge voltage fault: A battery pre-charge voltage fault. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery port voltage and cable connection. Force-shutdown and restart the system. - 867 — Battery under-voltage fault: A battery under-voltage fault. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery port voltage and cable connection. Force-shutdown and restart the system. - 868 — Battery cell voltage imbalance: A battery cell voltage imbalance fault. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery port voltage and cable connection. Force-shutdown and restart the system. - 870 — Battery cable connection fault: A battery cable connection fault. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery port voltage and cable connection. Force-shutdown and restart the system. - 900 · 901 — BDC temperature sensor warning: A battery (BDC) temperature-sensor warning. (Sungrow groups these codes under a single remedy.) — Fix: Check and clean the heat sink, verify the location is not in sunlight and the ambient temperature is below 45 °C, then restart. - 906 — Transformer direction recognition error: The transformer direction was recognised incorrectly. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 909 — Low SOH (State of Health) warning: The battery's State of Health is low. — Fix: The inverter stays grid-connected and charge/discharge is normal. The battery is beyond the scope of the warranty — it is recommended to contact the distributor for replacement. - 910 — FRAM2 warning: A FRAM2 memory warning. — Fix: Restart the inverter. - 932 — Battery over-voltage warning: A battery over-voltage warning. — Fix: The inverter stays grid-connected. Charging has stopped but discharging is allowed. The system resumes after some discharging. - 933 — Battery over-temperature warning: A battery over-temperature warning. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery's ambient temperature. Wait for recovery or restart. - 934 — Battery under-temperature warning: A battery under-temperature warning. — Fix: The inverter stays grid-connected but charge/discharge has stopped. Check the battery's ambient temperature. Wait for recovery or restart. - 935 — Battery charge/discharge over-current warning: A battery charging/discharging over-current warning. — Fix: The inverter can still connect to the grid but charge/discharge has stopped. Wait a moment for recovery or restart the system. - 937 — Battery tray voltage imbalance warning: A battery tray voltage imbalance warning. — Fix: The inverter stays grid-connected and charge/discharge is normal. Check whether the battery cable connection is correct. - 939 — Battery under-voltage warning: A battery under-voltage warning. — Fix: The inverter stays grid-connected. Discharging has stopped but charging is allowed. The system resumes after some charging. - 964 — Battery internal warning: An internal battery warning. — Fix: Consult the battery manufacturer for a solution. - 001 (SH) — Grid over-voltage: SH hybrid series: grid over-voltage. — Fix: The inverter reconnects after the grid recovers. If frequent, measure the grid voltage and contact the utility company or Sungrow. Verify the protection parameters and AC cable cross-section. - 002 (SH) — Grid under-voltage: SH hybrid series: grid under-voltage. — Fix: Generally reconnects after the grid recovers. If frequent, measure the grid voltage and contact the utility company. Verify the protection parameters and AC cable connections. - 003 (SH) — Grid over-frequency: SH hybrid series: grid over-frequency. — Fix: Generally reconnects after recovery. If frequent, measure the grid frequency and contact the utility company. Verify the protection parameters. - 004 (SH) — Grid under-frequency: SH hybrid series: grid under-frequency. — Fix: Generally reconnects after recovery. If frequent, measure the grid frequency and contact the utility company. Verify the protection parameters. - 005 (SH) — No grid: SH hybrid series: no grid detected. — Fix: Check the grid power supply reliability, AC cable connections, live/neutral wire placement, and AC switch status. Contact Sungrow or your solar installer if it persists. - 006 (SH) — Over-high leakage current: SH hybrid series: leakage current too high. — Fix: Can be caused by poor sunlight or a damp environment — the inverter reconnects after conditions improve. If the environment is normal, check that the AC and DC cables are well insulated. If the alarm persists, contact Sungrow or your solar installer. - 007 (SH) — Grid abnormal: SH hybrid series: grid abnormal. — Fix: Generally reconnects after recovery. If frequent, measure the grid frequency and contact the utility company. Contact Sungrow or your solar installer if it persists. - 008 (SH) — Grid voltage unbalance: SH hybrid series: unbalanced grid voltage. — Fix: Generally reconnects after recovery. If frequent, measure the grid voltage; if unbalanced, contact the utility company. Modify the settings via the app if within the permissible range. - 009 (SH) — PV reverse connection fault: SH hybrid series: PV reverse connection fault. — Fix: Check the string polarity; adjust only when solar radiation is low and string current is below 0.5 A. Verify that strings on the same MPPT have the same module count. Contact Sungrow if it persists. - 010 (SH) — PV reverse connection alarm: SH hybrid series: PV reverse connection alarm. — Fix: Check the string polarity; adjust only when solar radiation is low and string current is below 0.5 A. Verify that strings on the same MPPT have the same module count. Contact Sungrow if it persists. - 011 (SH) — PV abnormal alarm: SH hybrid series: PV abnormal alarm. — Fix: Check for shaded PV modules; remove shade and clean them. Check for abnormal module aging. Contact Sungrow or your solar installer if it persists. - 012 (SH) — High ambient temperature: SH hybrid series: high ambient temperature. — Fix: Avoid direct sunlight; clean the air ducts; check for a fan alarm via the app and replace the fan if needed. Contact Sungrow or your solar installer if it persists. - 013 (SH) — Low ambient temperature: SH hybrid series: low ambient temperature. — Fix: Stop and disconnect the inverter. Restart it when the ambient temperature is within the permissible range. - 014 (SH) — Low ISO resistance: SH hybrid series: low insulation (ISO) resistance. — Fix: Wait for recovery. Verify the protection value via the app complies with regulations. Check the PV cable insulation. Clear any water/vegetation on site. Contact Sungrow if it persists. - 015 (SH) — Grounding cable fault: SH hybrid series: grounding cable fault. — Fix: Check the AC cable connections. Verify the grounding-cable wire-core insulation. Contact Sungrow or your solar installer if it persists. - 016 (SH) — Arc fault: SH hybrid series: DC arc fault. — Fix: Disconnect the DC inputs and check the cables for damage, terminal connections, fuses, and burnt modules. Reconnect and clear via the app. Contact your installer if it persists. - 017 (SH) — Off-grid load over-power: SH hybrid series: off-grid load over-power. — Fix: Reduce the power of loads connected at the off-grid port, or remove some loads. If the alarm persists, contact Sungrow or your solar installer. - 018 (SH) — Reverse Smart Energy Meter connection: SH hybrid series: Smart Energy Meter connected in reverse. — Fix: Check the meter polarity against the cable-port markings and correct it if needed. Verify the meter is connected at the grid connection point. Contact Sungrow or your solar installer if it persists. - 019 (SH) — Smart Energy Meter communication error: SH hybrid series: Smart Energy Meter communication error. — Fix: Check the meter communication cable and terminals for abnormality, and reconnect the communication cable. Contact Sungrow or your solar installer if it persists. - 020 (SH) — Grid confrontation: SH hybrid series: grid confrontation. — Fix: Check whether the AC output port is connected to the actual grid; if so, disconnect it. If the alarm persists, contact Sungrow or your solar installer. - 021 (SH) — Parallel communication alarm: SH hybrid series: parallel communication alarm. — Fix: Check the communication cable and terminal connections for abnormality, and reinstall the communication cable. Contact Sungrow or your solar installer if it persists. - 022 (SH) — BMS communication error: SH hybrid series: battery management system (BMS) communication error. — Fix: Check the communication cable and terminal connections for abnormality, and reinstall the communication cable. Contact Sungrow or your solar installer if it persists. - 023 (SH) — Battery polarity reversed: SH hybrid series: battery polarity reversed. — Fix: Check the battery polarity is correct and correct it if necessary. If the alarm persists, contact Sungrow or your solar installer. - 024 (SH) — Battery alarm: SH hybrid series: battery alarm. — Fix: The battery generally recovers automatically. If persistent, address ambient-temperature issues or contact the battery manufacturer. - 025 (SH) — Battery abnormal: SH hybrid series: battery abnormal. — Fix: If the voltage is abnormal, check the battery's real-time voltage and contact the manufacturer or Sungrow. For temperature issues, improve heat dissipation. Contact the manufacturer if it persists. - 063 (SH) — System alarm: SH hybrid series: system alarm. — Fix: The inverter can operate normally. Check whether the related cable connections and terminals are abnormal, and whether the ambient environment is abnormal; take corrective measures if so. If the alarm persists, contact Sungrow or your solar installer. - 064 (SH) — System fault: SH hybrid series: system fault. — Fix: Wait for the inverter to recover. Disconnect the AC and DC switches or circuit breakers, then reconnect them after 15 minutes. If the alarm persists, contact Sungrow or your solar installer. --- ## Growatt — fault codes Source: https://solaranalytica.com/growatt-error-codes An independent reference compiled by Solar Analytica from Growatt documentation and field sources. Growatt shows faults two ways depending on model and firmware: newer inverters display a numbered Error code (1xx system, 2xx PV/DC, 3xx AC grid, 4xx hardware), while many single-phase units show a named message like “PV Isolation Low.” Where a fault has both, we list them together — and both are searchable. Safety note: never open the inverter or work on wiring under load; for a high-DC-voltage fault, switch off the DC isolator first, and leave internal repairs to a licensed installer. - 100 — Reference voltage fault: An internal 2.5 V reference-voltage fault — a hardware-level problem on the control board. — Fix: Restart the inverter (turn off AC, then the DC isolator, wait 5 minutes, and reverse). If it returns, the board needs servicing — contact your installer or Growatt. - 101 — Communication fault: Loss of data between the main (DSP) and slave processors inside the inverter. — Fix: Perform a hard reset: DC off → AC off → wait 5 minutes → restart. If it persists, the control board needs professional repair. - 102 — Master/slave data mismatch: The data received by the master and slave processors disagree, often triggered by an unstable grid. — Fix: Restart the inverter and check whether the grid is stable. If it recurs, contact your installer or Growatt. - 116 — EEPROM fault: A fault in the inverter's internal (EEPROM) memory. — Fix: Restart the inverter. If the fault remains, it needs servicing — contact your installer or Growatt. - 117 — Relay fault: The internal grid relay is stuck (contacts welded) or its coil has failed. — Fix: Restart once; if it returns, the relay or power board must be replaced by a technician. - 118 — Initialisation / model fault: The inverter failed to initialise correctly (model/config fault). — Fix: Restart the inverter. If it persists, contact your installer or Growatt. - 119 — GFCI device damage: The internal residual-current (GFCI/RCD) sensor is damaged. — Fix: Restart once. If it remains, the safety sensor is compromised — arrange repair promptly; don't ignore it. - 120 — HCT (current sensor) fault: The Hall-effect current sensor is reading inaccurately or has failed. — Fix: Restart the inverter. If it persists, the sensor on the mainboard needs replacement by a technician. - 121 — Slave processor communication loss: The master processor cannot receive data from the slave processor. — Fix: Restart the inverter. If the error persists, contact your installer or Growatt. - 122 — Bus voltage fault: The internal DC bus voltage is out of its normal range. — Fix: Restart the inverter. If it recurs, contact your installer or Growatt. - 201 · Residual I High — Residual (leakage) current high: Earth-leakage current from the PV system has exceeded the safety threshold. — Fix: Restart once. If it recurs, an installer should inspect the DC cabling for damaged or stripped insulation (including rodent damage) and check the array's isolation. - 202 · PV Voltage High — PV input voltage too high: The PV string voltage exceeds the inverter's maximum input rating. — Fix: Turn off the DC isolator. The string most likely has too many panels in series — your installer must re-check the string sizing against the inverter's maximum voltage. - 203 · PV Isolation Low — PV isolation (insulation) low: Low insulation resistance between the array and ground — most common in rain or high humidity. — Fix: If it clears once things dry out, moisture is getting in. Have an installer inspect the MC4 connectors for water ingress or corrosion, and check the array and inverter grounding. - 205 · PV Boost Broken — PV boost circuit broken: The DC-DC boost converter circuit is damaged. — Fix: This is a board-level fault — contact your installer, the warranty centre, or Growatt for repair. - 300 · AC V Outrange — Grid voltage out of range: The grid voltage is too high (often above ~255–270 V) or too low for the inverter to stay connected. — Fix: Usually clears when the grid returns to range. If it's frequent, your network voltage may be high — contact your installer or network operator; protection/volt-watt settings may need review (with the operator's consent). - 302 · No AC Connection — No AC connection: No grid is connected — a grid outage, an open main switch, or a missing phase / open neutral. — Fix: Check the AC main switch / supply main switch and confirm the grid is on. If the grid is present and it persists, have an installer check the AC wiring and connections. - 303 · PE Abnormal — PE (earth) abnormal: A grounding fault — the voltage between neutral and protective earth (PE) is too high. — Fix: Have a licensed electrician inspect the earth connection and measure ground resistance. Don't work on the earthing yourself. - 304 · AC F Outrange — Grid frequency out of range: The grid frequency is outside the permitted range (deviating from 50/60 Hz). — Fix: Usually a grid event that self-clears — common when running off a backup generator. If it's frequent on mains power, contact your network operator. - 408 · Over Temperature — Over temperature: The inverter's internal temperature has exceeded its limit. — Fix: Check the cooling fans and air vents for blockage, ensure good airflow, and keep the unit out of direct sun and confined spaces. If it persists in normal conditions, contact your installer. - Output High DCI — Output DC injection high: The DC component of the inverter's AC output current is too high. — Fix: Restart the inverter. If the warning persists, contact your installer or Growatt. - Auto Test Failed — Auto-test failed: The inverter's self-test (a grid-protection test required in some regions) did not pass. — Fix: Restart and let the test re-run. If it fails again, contact your installer — the grid-protection settings or a hardware check may be needed. --- ## GoodWe — fault codes Source: https://solaranalytica.com/goodwe-error-codes An independent reference compiled by Solar Analytica from GoodWe documentation and field sources. GoodWe shows faults as a numbered error code and/or a named fault depending on the model — on an LCD unit, short-press the front button and scroll to “Error”/“Fault”; on ET/EH/EHB hybrid units, check Alarms in the SolarGo app or the SEMS portal. Where a fault has both a number and a name, we list them together, and both are searchable. Safety note: earth and insulation faults (Isolation, Ground I, PE Loss) need a licensed electrician — don't keep resetting them; and for a PV over-voltage, switch off the DC isolator before anything else. - 1 — SPI failure: An internal communication (SPI bus) failure inside the inverter. — Fix: Restart the inverter (AC off, DC isolator off, wait 5 minutes, reverse). If it returns, it needs servicing — contact your installer or GoodWe. - 2 — EEPROM R/W failure: A read/write failure on the inverter's memory chip. — Fix: Restart the inverter. If the fault remains, it needs servicing — contact your installer or GoodWe. - 3 · Fac Failure — Grid frequency fault: The grid frequency is outside the inverter's permissible range. — Fix: The inverter restarts automatically once the grid frequency returns to normal. If it's frequent — common when running off a generator — contact your network operator. - 7 · 25 — Relay check failure: The inverter's grid relay failed its self-check. — Fix: Restart once. If it returns, the relay or power board needs replacement by a technician. - 12 — LCD communication failure: A communication error between the LCD/display and the master DSP. — Fix: Restart the inverter. If it persists, contact your installer or GoodWe. - 13 — DC injection high: The DC component of the AC output current exceeds the inverter's limit. — Fix: Restart the inverter. If the fault recurs, contact your installer or GoodWe. - 14 · Isolation Fail — Isolation failure: Insulation resistance between the PV array and ground is too low — most common in rain or high humidity. — Fix: If it clears once dry, moisture is getting in. An installer should switch off the DC isolator and measure the impedance from PV+ and PV− to earth; if it's low, inspect the PV wiring insulation and MC4 connectors for water ingress. Don't keep resetting it. - 15 · Vac Failure — Grid voltage fault: The grid voltage is outside the acceptable range for the inverter. — Fix: Often self-restores when the grid returns to range. If it's frequent, your network voltage may be high — contact your installer or network operator; protection settings may need review (with the operator's consent). - 16 — External fan failure: The external cooling fan has faulted. — Fix: Check the fan and air vents for blockage. If the fan is faulty it needs replacement — contact your installer. - 17 · PV Over Voltage — PV over-voltage: The PV array voltage exceeds the inverter's maximum input. — Fix: Switch off the DC isolator. The string likely has too many panels in series — your installer must re-check the string sizing against the inverter's maximum input voltage. - 19 · Over Temperature — Over temperature: The inverter's operating temperature has exceeded its safe limit. — Fix: Improve ventilation per the install guidelines, keep the unit out of direct sun and confined spaces, and check the fans aren't blocked. - 20 — Internal fan fault: An internal cooling-fan fault (IFAN). — Fix: Restart once. If it persists, the internal fan needs service — contact your installer or GoodWe. - 21 — DC bus high: The internal DC bus voltage is too high. — Fix: Restart the inverter. If it recurs, contact your installer or GoodWe. - 22 · Ground I Fail — Ground (residual) current failure: Residual-current (earth-leakage) protection has tripped — current is leaking to ground. — Fix: Switch off the DC isolator and have an installer inspect the PV string wiring insulation for wear or damage. If it persists after reconnection, call a specialist — don't keep resetting an earth fault. - 23 · Utility Loss — Utility (grid) loss: Loss of connection between the inverter and the utility grid — an outage or a disconnection. — Fix: Check the Solar Supply Main Switch and the AC isolator are on, and confirm the grid is working. If the grid is fine and it persists, have an installer check the AC wiring. - 24 · 31 — AC HCT (current sensor) failure: The AC current sensor (HCT) has failed. — Fix: Restart once. If it remains, the current sensor needs service — contact your installer or GoodWe. - 26 · 32 — GFCI failure: A failure in the leakage-current (GFCI) detection circuit. — Fix: Restart once. If it remains, the safety detection circuit is compromised and needs repair — arrange it promptly; don't ignore it. - 30 — Reference 1.5 V failure: The internal 1.5 V reference voltage is out of range. — Fix: Restart the inverter. If it persists, it needs servicing — contact your installer or GoodWe. - PE Loss — Protective earth (PE) loss: A missing or faulty protective-earth connection — possibly loose wiring, corrosion, or grounding-system damage. — Fix: This is an electrical-safety fault — have a licensed electrician diagnose and repair the grounding connection. Don't keep resetting it. - Device Failure — Internal device failure: A general internal device failure (shown for faults outside the listed codes). — Fix: Restart the inverter once. If it persists, note the exact code shown and contact your installer or GoodWe. --- ## Solis (Ginlong) — fault codes Source: https://solaranalytica.com/solis-alarm-codes An independent reference compiled by Solar Analytica from publicly available Solis (Ginlong) inverter documentation. It lists the alarm and fault codes a Solis inverter may display, what each means, and the documented resolution steps. Safety note: for Solis units in particular, never open the DC isolators under load — wait for low irradiance and confirm string current is below 0.5 A first. Anything involving wiring or opening the unit is licensed-electrician work; if in doubt, contact your installer. - LCD blank — No power on the LCD: The inverter shows no power on the LCD. - Init loop — Stuck on “initialising”: The inverter cannot start up — the LCD shows “initialising” continuously. - OV-G-V01–04 — Over grid voltage: The grid voltage is above the allowed limit. — Fix: AC cable resistance may be too high — change to a larger cable size. Adjust the protection limit only if permitted by the electricity company. If the fault occurs frequently, contact your solar installer. - UN-G-V01/02 — Under grid voltage: The grid voltage is below the allowed limit. — Fix: Use the user-define function to adjust the protection limit only if permitted by the electricity company. If the fault occurs frequently, contact your solar installer. - OV-G-F01/02 — Over grid frequency: The grid frequency is above the allowed limit. — Fix: Use the user-define function to adjust the protection limit only if permitted by the electricity company. If the fault occurs frequently, contact your solar installer. - UN-G-F01/02 — Under grid frequency: The grid frequency is below the allowed limit. — Fix: Use the user-define function to adjust the protection limit only if permitted by the electricity company. If the fault occurs frequently, contact your solar installer. - Reverse-GRID — Wrong AC polarity: The AC connection polarity is incorrect. — Fix: Check the polarity of the AC connector. Contact your solar installer. - Reverse-DC — Reverse DC polarity: The DC connection polarity is reversed. — Fix: Check the polarity of the DC connector. Contact your solar installer. - NO-GRID — No grid voltage: No grid voltage is detected. - OV-DC01–04 — Over DC voltage: The DC input voltage is above the allowed limit. — Fix: Reduce the number of modules in series. Contact your solar installer. - OV-BUS — Over DC bus voltage: The internal DC bus voltage is too high. — Fix: Restart the inverter and check the inductor and driver connections. Contact your solar installer. - UN-BUS01/02 — Under DC bus voltage: The internal DC bus voltage is too low. — Fix: Restart the inverter and check the inductor and driver connections. Contact your solar installer. - GRID-INTF01/02 — Grid interference: Grid interference is affecting the inverter. — Fix: Restart the inverter. If unresolved, the power board may need replacing — contact your solar installer. - OV-G-I — Over grid current: The grid current is above the allowed limit. — Fix: Restart the inverter. If unresolved, the power board may need replacing — contact your solar installer. - IGBT-OV-I — Over IGBT current: The IGBT current is above the allowed limit. — Fix: Restart the inverter. If unresolved, the power board may need replacing — contact your solar installer. - G-IMP — High grid impedance: The measured grid impedance is high. — Fix: Use the user-define function to adjust the protection limit only if permitted by the electricity company. Contact your solar installer. - DC-INTF / OV-DCA-I — DC input over-current: The DC input current is above the allowed limit. — Fix: Restart the inverter. Identify and remove the string feeding the faulty MPPT. If unresolved, the power board may need replacing — contact your solar installer. - IGFOL-F — Grid current tracking fail: The inverter failed to track the grid current. — Fix: Restart the inverter, or contact your solar installer. - IG-AD — Grid current sampling fail: The grid current sampling circuit failed. — Fix: Restart the inverter, or contact your solar installer. - OV-TEM — Over temperature: The inverter is over temperature. — Fix: Check ventilation around the inverter and whether it is in direct sunlight in hot weather. If the fault recurs frequently, contact your solar installer. - INI-FAULT — Initialisation system fault: A system fault occurred during initialisation. — Fix: Restart the inverter, or contact your solar installer. - DSP-B-FAULT — Main–slave DSP comms failure: Communication failed between the main and slave DSP. — Fix: Restart the inverter, or contact your solar installer. - 12power-FAULT — 12 V power supply fault: The internal 12 V power supply has faulted. — Fix: Restart the inverter, or contact your solar installer. - PV ISO-PRO01/02 — PV isolation protection: Low insulation resistance between the PV array and ground. — Fix: Remove all DC inputs, then reconnect and restart the inverter one string at a time. Identify which string causes the fault and check its insulation. Contact your solar installer. - ILeak-PRO01–04 — Leakage current protection: The leakage (residual) current exceeds the protection limit. — Fix: Check the AC and DC connections, and the cable connections inside the inverter. Contact your solar installer. - RelayChk-FAIL — Relay check fail: The relay self-check failed. — Fix: Restart the inverter, or contact your solar installer. - DCinj-FAULT — High DC injection current: The DC injection into the AC output is too high. — Fix: Restart the inverter, or contact your solar installer. - Screen off — Screen off with DC applied: The screen is off although DC is applied — the inverter may be internally damaged. — Fix: Do not turn off the DC switches — doing so under load will damage the inverter. Wait for irradiance to drop, confirm string current is below 0.5 A with a clip-on ammeter, then turn off the DC switches. Damage from incorrect operation is not covered by warranty. Contact your solar installer. - AFCI self-test — AFCI module self-detect fault: The AFCI (arc-fault) module failed its self-detection. — Fix: Restart the inverter, or contact a technician. - Arcing — Arc detected in DC circuit: An arc was detected in the DC circuit. — Fix: Check the inverter connections for arcing, then restart the inverter. Contact your solar installer. --- ## SolaX Power (X1 / X3 string and hybrid inverters) — fault codes Source: https://solaranalytica.com/solax-inverter-error-codes SolaX X1 (single-phase) and X3 (three-phase) string and hybrid inverters report problems as named text faults — for example "Grid Lost Fault", "Grid Volt Fault" or "Isolation Fault" — shown on the inverter display and logged in the SolaX Cloud app under fault/alarm history, rather than as numbered codes. Many grid-side faults (Grid Lost, Grid Volt, Grid Freq, AC5M/AC10M) are protective trips that clear on their own once your mains supply returns to normal; others — isolation, relay, internal memory and most battery/charger faults — point to a hardware or wiring issue that needs investigation. Exact wording and behaviour can vary a little between models and firmware versions, so always check your specific model's manual. Safety note: This list is general reference only, not a repair guide. Anything involving DC isolators, the AC supply, battery wiring, or opening the inverter is licensed-electrician work under AS/NZS 4777 and AS/NZS 5033 — do not attempt it yourself. Solar PV and battery DC can remain lethal even when the grid is off. If a fault recurs, or you see an Isolation, RCD or relay fault, stop and call your installer or a licensed solar electrician. - Grid Lost Fault — Grid connection lost: The inverter can no longer detect a stable grid supply, so it has safely shut down. This is anti-islanding protection required under AS/NZS 4777.2 — it stops your system back-feeding the network during a blackout, which could be lethal to line workers. Most often caused by a genuine grid outage, a tripped solar supply breaker, or an AC isolator switched off. — Fix: Usually clears itself automatically once the grid returns to normal. Check whether the wider home/street has power and whether the rooftop-solar AC isolator and the 'Solar Supply Main Switch' on the switchboard are on. If those are on and the fault persists with the grid present, have a licensed electrician investigate the AC connection — do not open the unit yourself. - Grid Volt Fault — Grid voltage out of range: The mains voltage at your property is outside the allowable window the inverter is permitted to operate within. In Australia a common cause is high voltage (over ~253 V) on sunny afternoons when many local solar systems export at once, forcing inverters to trip. This is correct, code-mandated behaviour, not a defect. — Fix: Normally clears by itself when voltage stabilises. If it recurs regularly, download the voltage data from SolaX Cloud and report it to your network distributor (DNSP) — persistent high voltage is a network issue they must address. An accredited installer can also check whether export limiting or settings need adjusting. AC-side checks are licensed-electrician work. - Grid Freq Fault — Grid frequency out of range: The grid frequency has drifted outside the permitted band (nominal 50 Hz in Australia), so the inverter has disconnected for safety. This is almost always a network/supply condition rather than an inverter fault. (Some SolaX manuals print the description for this fault as 'Grid Voltage out of range' — a documentation typo; the fault itself is frequency-related.) — Fix: Generally clears automatically once the grid frequency returns to normal. If it happens repeatedly, log it via SolaX Cloud and report to your installer or network distributor. No DIY intervention required. - PLL Lost Fault — Grid synchronisation lost: The inverter could not lock onto (synchronise with) the grid's voltage/frequency waveform — SolaX describes this internally as 'the grid is not good'. Usually a symptom of an unstable or poor-quality grid supply rather than a hardware fault. — Fix: Typically recovers on its own when the grid stabilises. If it keeps recurring, have your installer review grid quality and the AC connection. Not a homeowner repair. - AC5M Volt Fault / AC10M Volt Fault — Sustained grid voltage out of range (5 / 10 minute average): The grid voltage averaged over a 5-minute (AC5M) or 10-minute (AC10M) window has exceeded the allowable limit — a longer-term over/under-voltage protection separate from the instantaneous trip. — Fix: Resolves automatically when the average grid voltage returns to normal. Persistent occurrences indicate sustained network voltage problems — capture SolaX Cloud data and report to your installer/DNSP. - Isolation Fault — DC insulation resistance too low: The inverter has measured low insulation resistance between the DC (PV/battery) circuit and earth. This is a safety-critical fault that usually points to moisture ingress, a damaged cable, or a degraded connector/panel — there may be a current leakage path to ground. — Fix: Do NOT restart repeatedly and do not investigate yourself — DC isolation faults are licensed-electrician work and PV DC can be lethal. Switch the system off at the AC and DC isolators and arrange a licensed solar technician to test the array insulation and wiring. Common after heavy rain; if it doesn't self-clear once things dry out, it needs inspection. - RCD Fault — Residual current (earth leakage) fault: The inverter's internal residual-current monitoring detected leakage current to earth above the safe threshold. Like an isolation fault, this is a safety protection that can indicate a wiring or insulation problem. — Fix: Treat as safety-critical. Switch off and have a licensed electrician check DC and AC impedance/insulation. Do not bypass or repeatedly reset it. Not a DIY task. - PV Volt Fault — PV input voltage out of range: The DC voltage coming from the solar array is outside the inverter's allowable input window. This can be caused by string-design issues (for example too many panels in a string, which pushes voltage high in cold conditions) or an abnormal string condition. — Fix: Have your accredited installer compare the measured string voltage against the inverter's rated MPPT/maximum input range. If it is out of spec, the array design or a string fault needs review. Working on DC strings/isolators is licensed-electrician work. - PV Config Fault — PV input configuration error: The PV connection/configuration setting (SolaX: 'PV Connection Setting Fault') does not match how the strings are actually wired — for example parallel vs independent MPPT input settings. — Fix: Have your installer confirm the PV input configuration setting matches the physical wiring and correct it. A restart may clear a transient case, but a recurring fault needs the configuration checked. - Bus Volt Fault — Internal DC bus voltage out of range: The internal DC bus voltage inside the inverter is outside its normal operating range. Can be a transient event tied to PV input fluctuations, or an internal hardware issue. — Fix: A controlled power cycle can clear a transient case: turn off AC, then the DC isolator, wait ~60 seconds, then restore DC and AC. Confirm PV input is within the rated range. If it returns, contact your installer — internal repairs are not a homeowner task. - Over Temperature Fault — Inverter over temperature (Temp Over Fault): The inverter has exceeded its safe internal operating temperature and has derated or shut down to protect itself. Common in hot weather, poor ventilation, or full-sun wall mounting. — Fix: Check the inverter is not in direct sun or boxed in, that there is clear airflow around it, and that the cooling fan runs. It generally recovers once it cools. If it overheats in normal conditions or the fan is silent, have it inspected — do not open the enclosure. - Fan Fault / Fan Speed Fault — Cooling fan fault or abnormal fan speed: A cooling fan (Fan1/Fan2) is not running or is running outside its normal speed range. Often caused by dust, debris or insects blocking the fan, or a worn fan. — Fix: If safe and accessible externally, check for dust/debris around the fan vents; a restart may clear a transient case. If the fan stays faulty the unit can overheat — have your installer replace or service it. Do not open the inverter yourself. - Overload Fault — EPS / backup output overloaded: While running on battery backup (EPS mode during a grid outage), the connected load drew more power than the inverter can supply, so it shut the backup output down to protect itself. — Fix: Switch off high-power appliances on the backup circuit (kettles, ovens, aircon, pumps) so the load is within the inverter's EPS rating, then press ESC to restart. If it trips with only modest load, have the backup circuit and settings reviewed by your installer. - EPS OCP Fault — Overcurrent in EPS (backup) mode: An overcurrent was detected on the backup (EPS) output — for example from a large inrush/surge or a non-linear load when running off battery during an outage. — Fix: Ensure backup loads are within range and remove problematic high-surge or non-linear loads, then restart. If it persists, the backup wiring/loads need an installer's review. - Relay Fault — Grid relay fault: A self-test of the internal grid-connection relay has failed. The relay is a safety device that disconnects the inverter from the grid, so the unit will not operate until it passes. On X3 (three-phase) hybrids it can also be triggered by a poorly connected neutral or three-phase imbalance. — Fix: A restart may clear a one-off self-test glitch. If it returns, this is an internal hardware fault — shut the system down and contact your installer for inspection/repair. Not a DIY task. - TZ Protect Fault — Hardware overcurrent protection tripped: A fast hardware overcurrent protection (Tripzone) has activated. Sometimes a transient event, sometimes an internal fault. — Fix: Allow a moment for it to clear; a controlled power cycle (AC off, DC off, wait, restore) may reset a transient case. If it recurs, have it inspected by your installer — internal repairs are licensed work. - Inv OCP Fault — Inverter overcurrent protection: The inverter detected an output overcurrent and tripped to protect itself. — Fix: Wait briefly to see if it self-clears. A controlled power cycle may help. If it keeps recurring, contact your installer — do not open the unit. - SW OCP Fault — Software-detected overcurrent: The control software detected an overcurrent condition and shut down as a protective measure. — Fix: Power the system down (PV, battery and grid) and restart. If the fault returns, escalate to your installer for diagnosis. - DCI / DCI OCP / RC Fault — DC injection (DCI) fault: The inverter detected excessive DC current being injected into the AC grid (or a fault in the DCI sensing). Limiting DC injection is a grid-compliance safety requirement. — Fix: May self-recover if transient. A controlled restart can help. Persistent DCI faults need an installer/electrician to investigate — this affects grid compliance and is not a homeowner repair. - CT / Meter Fault — CT clamp or smart meter not detected: The inverter cannot communicate properly with the current transformer (CT) clamp or smart meter used to measure import/export (SolaX: 'the CT or the meter is not connected well'). This affects export limiting and energy monitoring rather than basic generation. — Fix: Have your installer check the CT/meter wiring, orientation and communication connection. Do not open the inverter; CT/metering work on the switchboard is licensed-electrician work. - SPI / SCI Fault — Internal communication fault (master/slave DSP): An internal communication link between the inverter's processors (SPI between master/slave DSP, or SCI) has dropped. Often a transient glitch that recovers by itself, typically within a few minutes. — Fix: Frequently self-recovers; a controlled power cycle (AC off, DC isolator off, wait ~60 s, restore) usually clears it. If it returns repeatedly, contact your installer. - CAN1 Fault / C1 CAN Fault — Battery / charger CAN communication fault: The inverter has lost CAN-bus communication with the battery (BMS) or internal charger module. On a hybrid system this typically means the battery has dropped offline — common causes include a loose CAN cable, the wrong battery type selected in inverter settings, or a missing 120-ohm termination resistor. — Fix: Check the battery communication cable is seated and the battery is switched on. A correct shutdown/startup sequence of the battery, DC and AC per the manual can re-establish comms. If it persists, contact your installer — battery wiring is licensed work. - Inv EEPROM / Mgr EEPROM / C1 EEPROM Fault — Internal memory (EEPROM) fault: An internal memory chip (inverter, manager or charger EEPROM) has reported a read/write error. Can occasionally be transient but often indicates a hardware fault. — Fix: A power cycle may clear a one-off case. If it persists it generally requires a service/replacement by SolaX or your installer — not a homeowner repair. - Sample Fault — Detection/sampling circuit fault: An internal measurement (sampling) circuit has returned readings outside expected bounds (SolaX: 'the detection circuit fault'), so the inverter cannot trust its own sensing and has stopped. — Fix: A controlled power cycle may clear a transient case. If it recurs, this is an internal hardware fault for your installer/SolaX — do not open the unit. - C1 Temp High / C1 Temp Low — Battery charger over / under temperature: The internal battery charger module is too hot (blocked airflow, high charge current, hot environment) or too cold to operate safely. — Fix: For over-temperature, clear any blocked vents and improve ventilation/ambient conditions; it recovers once it cools. For under-temperature, the unit resumes once it warms into its operating range. Persistent issues need an installer's review. - C1 Bat OVP — Battery over-voltage: The battery voltage has risen above the charger's safe limit, so charging stopped to protect the battery and inverter. — Fix: Usually self-recovers once the battery voltage settles after the load balances. If it keeps occurring, have your installer check the battery and charge settings — battery work is licensed. - C1 Bus OVP / C1 Boost OVP — Charger bus / boost over-voltage: An internal voltage rail in the battery charger (DC bus or boost stage) has exceeded its limit and the charger has stopped to protect itself. — Fix: Often self-recovers if transient. If it persists, it points to an internal charger fault for your installer/SolaX. Not a DIY repair. - C1 Charger OCP / C1 Boost OCP — Charger / boost overcurrent: An overcurrent was detected in the battery charger or its boost stage, tripping protection. — Fix: Allow time to clear; a restart may help a transient case. Recurring charger overcurrent needs an installer's inspection — internal repairs are licensed work. - DM9000 Fault — Network DSP fault: The internal networking/DSP component (DM9000) has faulted, typically affecting communication/monitoring functions. — Fix: A full controlled system restart (PV, battery, grid) may clear it. If it persists, contact your installer for service. - RTC Fault — Real-time clock fault: The inverter's internal real-time clock (date/time) has faulted. Mainly affects time-stamping, scheduling and time-of-use battery functions rather than basic generation. — Fix: A restart and re-syncing the time via SolaX Cloud often clears it. If it returns (commonly a flat internal backup battery), arrange service through your installer. --- ## Deye (SUN-series string & hybrid inverters) — fault codes Source: https://solaranalytica.com/deye-inverter-fault-codes Deye builds the SUN-series string and hybrid inverters sold across Australia, and the same hardware and fault-code family is widely rebadged under other brands (Sunsynk being the best-known example), so this list applies broadly. Faults appear on the screen or app as an "F" code (F01-F64). Most are self-clearing grid or operating-mode events; a smaller group point to a genuine wiring, PV, battery or hardware problem. Important: the F-number for a given fault is NOT stable across firmware versions and regional model variants of the same SG04LP3 hardware. Direct decoding of Deye's own current manuals shows this clearly: the official Australian (2022) and global EU (2026) manuals BOTH number the ground-fault/start self-check as F07 (DC_START_FAILURE), use F46 for a battery fault, and contain NO F08 and NO F35 at all - whereas the firmware actually running on many deployed units (and the Sunsynk rebadge of the same board) reports the GFDI relay check as F08 and "no grid" as F35. This list documents the codes as owners and installers most commonly see them in the field, but every number must be confirmed against the exact manual and firmware for your specific unit before acting. Safety note: A Deye inverter has live PV DC, battery DC and grid AC inside it even when the screen is dark. Doing the basics - reading the code, checking it isn't a momentary grid event, and a clean restart - is fine for an owner, but anything involving the DC isolator, AC wiring, opening the unit, or working on PV/battery cabling is licensed-electrician (and CEC-accredited installer) territory in Australia. If a code keeps returning after a restart, log it and call your installer rather than persisting. - F08 — GFDI relay failure: The inverter's ground-fault detection (GFDI) relay has failed a self-test, or the neutral/earth bonding doesn't match the configured grid type. On deployed firmware and rebadged (Sunsynk) units this is one of the most-reported codes and is very often a grid-type setting mismatch (e.g. set to 120/240V split-phase when the system is actually single-phase) rather than a true hardware fault. (Note: the current official Deye AU and EU manuals do NOT list an F08 - they number the equivalent start/ground self-check as F07. Confirm against your unit's firmware.) — Fix: First confirm the configured Grid Type matches the actual supply (single phase vs split/three phase) - on single-phase units, setting Grid Type to Single Phase commonly clears it. Power-cycle the inverter cleanly (ideally restart from battery with AC and PV DC isolated). If it persists, the neutral-to-earth bonding at the backup/load port and the GFDI relay itself need checking - that is electrical work for your CEC-accredited installer or a licensed electrician; do not open the unit or alter earthing yourself. - F13 — Working mode / grid mode changed: An informational event, not a hardware fault. The official manual logs it when the grid type or frequency setting changes, when the battery mode is switched to 'No battery', or (on some older firmware) when the system work mode changes. It normally clears itself. — Fix: Usually no action needed - it clears automatically. If it stays, turn off the DC isolator and AC switch, wait about one minute, then turn the AC and DC back on. If it still won't clear, contact your installer. - F15 — AC over-current (software): The inverter's software protection has detected excessive current on the AC side (listed in the official manual as 'AC over current fault of software'). Can be triggered by a heavy backup or common load, or by an AC sensing issue. — Fix: Check that backup-load and household-load demand are within the inverter's rated range and reduce load if needed, then restart. If it persists it points to an internal sensor or loose AC connection - that is for your installer or a licensed electrician, not an owner. - F16 — AC leakage current fault: The residual-current monitor has detected earth-leakage current above its threshold (official manual: 'AC leakage current fault'), which can indicate a PV array insulation problem or moisture in connectors. The manual's listed remedy focuses on the PV-side cable ground connection. — Fix: Restart the inverter; transient leakage (e.g. damp panels in the morning) often clears on its own - the manual suggests restarting two or three times. If it keeps returning, the PV array, cabling and earthing need inspection by your CEC-accredited installer - leakage faults can indicate a genuine insulation hazard, so don't ignore a persistent one. - F18 — AC over-current (hardware): A hardware-level over-current trip on the AC side (official manual: 'AC over current fault of hardware'), typically from too much load on the backup and/or common-load outputs. — Fix: Check that backup-load power and common-load power are within the allowed range, reduce load, and restart to see if it clears. If it persists, contact your installer. - F20 — DC over-current (hardware): A hardware-level over-current trip on the DC side (PV or battery) - official manual: 'DC over current fault of the hardware'. Common when an off-grid/backup system is started into a large load, where inrush current briefly exceeds limits. — Fix: Check the PV and battery connections. If it appeared on off-grid startup with a big load, reduce the connected load. Turn off the DC isolator and AC switch, wait one minute, then turn them back on. If it persists, contact your installer; DC isolator and cabling work is licensed-electrician work. - F22 — Emergency stop / remote shutdown (Tz_EmergStop_Fault): The inverter has been shut down by a remote-control or emergency-stop signal - it is being commanded off, not failing. The official manual states 'it tells the inverter is remotely controlled'. — Fix: This indicates remote control is active. Contact your installer to confirm why the remote-shutdown signal is present before trying to override it. - F23 — Transient leakage / GFCI over-current (Tz_GFCI_OC_Fault): A transient earth-leakage (residual-current) over-current event, often linked to PV-side earthing. Confirmed in the official manual as 'Tz_GFCI_OC current is transient over current / leakage current fault'. — Fix: Check the PV-side cable ground connection. Restart the system two or three times to see if the transient clears. If the fault remains, have your installer inspect PV earthing and insulation - persistent leakage is a safety item. - F24 — DC insulation / isolation impedance failure: PV insulation resistance to earth is too low - the array's isolation impedance has dropped (official manual: 'DC insulation failure - PV isolation resistance is too low'), which can mean a damaged cable, water ingress, or a faulty panel/connector. — Fix: Check that PV panel-to-inverter connections are firm and correct and that the inverter's PE (earth) cable is properly connected to ground. This is an insulation safety fault: have your CEC-accredited installer test the array. Do not handle DC cabling or open the unit yourself. - F26 — DC busbar unbalanced: The internal DC busbar is unbalanced. The official manual notes it is logged when load across the phases is very uneven, and that it can also indicate DC leakage current. — Fix: Wait a short while and check whether it normalises. Where possible, balance the loads across phases (or across L1/L2 on split-phase). Restart the system two or three times if it persists, then contact your installer. - F29 — Parallel CAN bus fault: A communication fault on the parallel-link (CAN) bus between inverters in a multi-unit/parallel system. The official manual notes it is normal to see this briefly while a parallel system is powering up, and it clears once all units are ON. — Fix: On startup, ignore it if it self-clears once all inverters are running. If it stays, check the parallel communication cable connections and that each inverter's communication address is set correctly. Contact your installer if it persists. - F34 — AC overload fault: The connected load exceeds what the inverter can supply (official manual: 'AC Overcurrent fault'), typically on the backup/EPS output. A common owner-facing code when too many appliances run at once on backup power. — Fix: Reduce the load so it sits within the inverter's rated output, then let it recover or restart. Check what was running when it tripped - large motors/heaters are usual culprits. If it trips with modest load, contact your installer. - F35 — No AC grid (AC_NoUtility_Fault): The inverter cannot detect a valid utility grid - i.e. the grid is absent or out of acceptable voltage/frequency range. Often simply a grid outage or a tripped supply breaker; on three-phase units it can also be caused by incorrect phase rotation/sequence. (Note: this F35 numbering is from deployed/Sunsynk firmware; the current official Deye manuals do not list an F35 - confirm against your unit.) — Fix: Confirm whether grid power is actually present and that the AC supply breaker/isolator hasn't tripped. For a genuine outage, a hybrid system should switch to backup automatically and the code clears when the grid returns. If grid is present but the inverter still reports no utility, the AC connection (and on three-phase, the phase sequence) needs checking by a licensed electrician. - F41 — Parallel system stop: In a parallel installation, one inverter has shut down, which causes the other paralleled inverters to report F41 and stop as a group (official manual: 'if there is 1 pcs hybrid inverter shutdown, all hybrid inverters will report F41'). — Fix: Check the working status of each hybrid inverter in the parallel group to find which unit went down. Resolve that unit's underlying fault. If the cause isn't clear, contact your installer. - F42 — AC line low voltage: Measured grid (AC line) voltage is below the allowed range (official manual: 'AC line low voltage / grid voltage fault'). Frequently a grid-side condition (sagging supply) rather than an inverter fault. — Fix: Check whether the AC voltage is within the standard range and that the grid AC cables are firmly and correctly connected. Persistent under-voltage with a healthy grid, or any cabling check, is for a licensed electrician / your installer. - F46 — Backup battery fault: A fault with the connected battery (or batteries). The official Deye AU and EU manuals decode F46 as 'backup battery fault' and advise checking each battery's status - voltage, SOC and parameter settings - and making sure all parameters match. (Earlier third-party lists mislabelled F46 as 'AC under-voltage'; the decoded official manuals do not support that - treat F46 as a battery fault.) — Fix: Check each battery's status - voltage, state of charge and configured parameters - and make sure all units are set up consistently. If the fault persists, contact your installer to inspect the battery and its settings; battery DC work is licensed-electrician territory. - F47 — AC over-frequency: Grid frequency is above the allowed range, so the inverter disconnects per grid-protection (anti-islanding) rules. Usually a grid-side event. — Fix: Check whether the frequency is within specification and that AC cables are firmly connected. This is normally a transient grid condition that clears itself; if it recurs constantly, contact your installer. - F48 — AC under-frequency: Grid frequency is below the allowed range, so the inverter disconnects per grid-protection rules (official manual: 'AC lower frequency - grid frequency out of range'). Usually a grid-side event. — Fix: Check whether the frequency is within specification and that AC cables are firmly connected. Generally a transient grid condition that self-clears; if it persists, contact your installer. - F55 — DC bus voltage too high: The internal DC bus (busbar) voltage is too high (official manual: 'DC busbar voltage is too high - BUS voltage is too high') - typically because battery voltage or PV input voltage is above the allowed range. — Fix: Check whether the battery voltage is too high and confirm the PV input voltage is within the inverter's allowed range (over-sized/cold strings can push voltage up). If string voltage is the cause, your installer needs to review the array design. DC cabling work is licensed-electrician work. - F56 — DC bus voltage too low: The internal DC bus (busbar) voltage is too low - most often a flat or very low battery, or insufficient PV. Confirmed in the official manual as 'DC busbar voltage is too low - battery voltage low'. — Fix: Check whether the battery voltage is too low; if so, allow PV or the grid to charge the battery back up. If voltage stays low with a healthy battery, contact your installer. - F58 — BMS communication fault: Communication between the hybrid inverter and the battery BMS has been lost. The official manual flags it as a fault when the 'BMS_Err-Stop' protection is enabled and the BMS link drops (e.g. wrong comms cable, wrong battery protocol, or a loose RJ45). — Fix: Check the comms cable and connector between inverter and battery, and that the correct battery brand/protocol is selected. The 'BMS_Err-Stop' item can be disabled on the LCD if you don't want a comms drop to stop the inverter, but the underlying cause should still be fixed. Contact your installer if it persists. - F63 — ARC fault (AFCI): The arc-fault detection (AFCI) circuit has detected a possible DC arc on the PV side. The official manual notes this detection is enabled for the US market; many AU units will not raise it. — Fix: Check the PV module cable connections, then clear the arc fault from the menu. Because an arc indicates a potentially dangerous loose/damaged DC connection, have your CEC-accredited installer inspect the PV wiring before returning the system to service. Do not handle DC cabling yourself. - F64 — Heat-sink high temperature failure: The inverter's heat sink is too hot and it has shut down to protect itself (official manual: 'Heatsink high temperature failure - heatsink temperature is too high') - usually caused by a hot/poorly ventilated install location or blocked airflow. — Fix: Check whether the surrounding temperature is too high and that airflow around the unit isn't blocked (clear vents, provide shade/ventilation). Turn the inverter off for about 10 minutes to cool, then restart. If it keeps overheating in normal conditions, contact your installer. --- ## Enphase (IQ-series microinverters) — fault codes Source: https://solaranalytica.com/enphase-microinverter-error-codes Enphase IQ-series microinverters don't show numeric fault codes the way a string inverter does. Instead, each unit reports a plain-language event to the IQ Gateway, which you then see against the affected panel in the Enphase app or in Enlighten (the panel turns amber for a warning, red for a fault, or grey when it isn't reporting). Most of these events are the microinverter doing its job — disconnecting for safety when the grid drifts out of spec, or backing off in low light — and clear on their own once conditions return to normal. The list below covers the events Australian owners most commonly see and what each one means in plain English. Safety note: these are reference descriptions only, not repair instructions. A microinverter sits at the panel on the roof and works at the array's full DC and grid AC voltages. Anything involving the DC isolator, AC wiring, opening or handling the unit, or inspecting rooftop connections is licensed-electrician (and, for solar, CEC-accredited installer) work — never attempt it yourself. If an event won't clear, log it with your installer rather than going onto the roof. - AC Voltage Out Of Range — Grid voltage too high or too low: The microinverter is measuring AC (grid) voltage outside the limits set by its grid profile, so it disconnects and stops exporting until the grid settles back within range. In Australia high readings are extremely common on long suburban streets at midday when lots of solar is exporting and pushing local voltage up. — Fix: Usually self-correcting — grid voltage varies through the day and the unit reconnects on its own once it is back in spec for a sustained period. If it recurs daily across many panels, it points to a network/voltage problem on your street, which is a matter for your installer and the local network distributor (DNSP), not a fault in the microinverter. Persistent out-of-range readings on a single unit can indicate a faulty microinverter or its AC connection — diagnosis and any wiring work is for a licensed electrician/accredited installer. - AC Frequency Out Of Range — Grid frequency too high or too low: The microinverter is measuring a grid frequency outside its safe operating band (nominal 50 Hz in Australia) and goes offline as required by grid-protection rules. It must stay off until the grid has been continuously within limits for a set period; if frequency strays again during that window, the timer restarts. — Fix: Almost always a grid/network condition rather than a fault in your system, and it clears itself once the grid stabilises. If it affects all panels at once it is a grid event; if it persists on a single unit with the rest fine, the microinverter may be faulty. Any investigation of AC wiring is licensed-electrician work. - Grid Gone — No grid / AC supply detected: The microinverter has disconnected from the grid/mains because it cannot detect a valid supply, so it shuts down. Enphase units are anti-islanding by design and will not produce power without a stable grid present. This appears during a blackout, or when an AC isolator, breaker or RCD on the solar circuit has been switched off. — Fix: If the whole array reports it, check whether there is a power outage; production resumes automatically when the grid returns. If only one or a few panels report it while others are fine, it suggests a wiring or connection issue, or a failed unit. Checking or switching solar isolators/breakers and any AC wiring is licensed-electrician work. - DC Voltage Too Low — Not enough DC input from the panel: The microinverter is seeing DC input voltage from its solar module below the level needed to operate. This is completely normal early morning, late evening, in heavy shade, or on very overcast days. If it appears in good daylight, it can indicate a poor or broken DC connection between the panel and the microinverter, or — on a new system — that a grid profile still needs to be applied at commissioning before the units will produce. — Fix: If it clears as the light improves, no action is needed — it was just low irradiance. If it persists during strong daylight, the panel-to-microinverter DC connection may be loose, damaged or disconnected; inspecting or working on that connection on the roof is licensed-electrician / accredited-installer work. A newly installed system reporting this may simply need its grid profile applied by the installer. - DC Power Too Low — Panel producing too little power: Closely related to DC Voltage Too Low — the microinverter is measuring DC power below its operating threshold. Most often this is just low light (dawn, dusk, shade, cloud). If it occurs in full sun, it can point to a shaded, soiled or underperforming panel, or a degraded DC connection. — Fix: Expected and self-clearing in low-light conditions. If a panel shows it in bright sun while neighbours produce normally, note it for your installer to investigate. Any rooftop or DC-side inspection is licensed-electrician work. - DC Voltage Too High — Too much DC input from the panel: The microinverter reports DC input voltage from the solar module above its rated maximum. On a correctly matched panel/microinverter pairing this is unusual and generally suggests a microinverter malfunction or a module/wiring mismatch. — Fix: Not user-serviceable. If the condition persists, report it to your installer; on the roof, any inspection of the module or DC wiring is licensed-electrician / accredited-installer work. - GFI Tripped — Ground-fault current detected: The microinverter's built-in ground-fault (GFI) sensor has detected leakage current to earth during normal operation and has opened the circuit to protect against a fault. It can be triggered by moisture/weather, but a persistent trip points to damaged module insulation (such as cracked module glass), a damaged connector or cable, or water ingress. — Fix: A one-off after wet weather may clear (your installer can send a reset command via the Enphase app/Enlighten). A repeating GFI trip should be treated as a genuine insulation/earth fault and inspected promptly by a licensed electrician / accredited installer — do not attempt to reset or investigate it yourself on the roof. - DC Resistance Low - Power Off — Insulation resistance to earth too low: An insulation-resistance (IR) sensor in the microinverter measures the resistance to earth from the positive and negative DC inputs. If it drops below the acceptable threshold (around 7 kΩ on IQ units), the unit stops producing and latches off. On IQ8 units this shows as a solid red status LED (after DC power has been cycled), and the gateway keeps reporting the fault until it is cleared. Common causes are moisture ingress, damaged cabling/connectors, or degraded module insulation. — Fix: The condition must be cleared by command from the IQ Gateway (via the Enphase app / Enlighten device conditions and controls, or Enphase support) once the cause is resolved — it will not clear by itself. A short-lived case after rain may resolve, but a recurring or persistent one indicates a real insulation fault that needs a licensed electrician / accredited installer to find and rectify. Locating and repairing the fault on the array is not DIY work. - Over Temperature / Critical Temperature — Microinverter running too hot: An internal temperature measurement inside the microinverter is above its normal range. To protect itself it automatically reduces (derates) its power output, and in extreme cases shuts down, until it cools; full power resumes once the temperature falls to an acceptable level. Note this is an internal reading, not ambient air temperature (IQ8 units run at full power up to about 50 °C ambient and derate above that). It can be driven by very high roof temperatures or restricted airflow behind the panel. — Fix: Normally self-managing — output recovers once the unit cools. If a single unit repeatedly reports high temperature when others nearby don't, it may be failing; report it to your installer. No rooftop intervention should be attempted by the owner. - Microinverter Failed to Report — Gateway has lost contact with a microinverter: The IQ Gateway is no longer receiving data from one or more microinverters over the powerline communication (PLC) link, so the panel shows grey (not reporting). It can be caused by powerline-communication interference (e.g. a surge strip, noise source, or the gateway being plugged into a power board rather than a wall outlet), a tripped solar breaker/isolator, an AC wiring issue, or a failed unit — it does not necessarily mean the panel has stopped producing. — Fix: Often a communication hiccup that resolves on its own or after the gateway is power-cycled. If specific panels stay grey, it can indicate interference from other equipment, a circuit issue, or a faulty microinverter — diagnosis (and any breaker/wiring work) is for a licensed electrician / accredited installer. - Microinverter Not Detected / Not Found — New microinverter not discovered during commissioning: During or after installation the IQ Gateway / Enphase Installer App cannot find a microinverter to add it to the system. This is a commissioning-stage condition (the device shows as "not discovered") rather than a logged operational fault, and usually means the unit isn't yet powered, hasn't been given time to be discovered, or its serial wasn't scanned correctly. — Fix: An installer task: confirm the unit is installed on a powered panel, allow time for discovery, then re-scan/provision it in the Enphase Installer App (the app provides on-screen guidance when a device fails to be discovered). Any work at the array or switchboard is licensed-electrician / accredited-installer work. - Device Produced No Power — No energy generated in the last 24 hours: A microinverter that previously produced has generated no power within the last 24 hours. Causes range across the grid (a profile/voltage/frequency condition keeping it off), the AC side (a tripped breaker or isolator), or a failed unit. — Fix: Check whether a solar breaker/isolator is off and whether the rest of the array is also affected. Widespread cases usually trace to a grid or switchboard issue; an isolated case can mean a failed microinverter or wiring fault. Switching breakers/isolators and any wiring work is licensed-electrician work; otherwise refer it to your installer. - Gateway / Envoy Not Reporting — IQ Gateway not sending data to Enphase: The IQ Gateway (Envoy) itself has stopped uploading data to the Enphase cloud, so the whole system appears offline in the app. This is almost always an internet/connectivity problem (router, Wi-Fi, or the gateway's own connection) rather than a solar production fault — your panels may still be generating normally. — Fix: Owner-safe checks only: confirm your home internet is working (check it on another device), then restart your router and the gateway (mains power cycle, then wait around 10 minutes). If you've changed router or Wi-Fi password, the gateway needs reconnecting via the Enphase app (your installer can guide this). If it stays offline after that, contact your installer. --- ## Sigenergy (SigenStor) — fault codes Source: https://solaranalytica.com/sigenergy-sigenstor-fault-codes Sigenergy's SigenStor is a newer all-in-one system that stacks the PV inverter, battery, and energy controller in one tower, so its alarms cover the full chain from the DC strings through the battery to the grid connection. Codes are shown in the mySigen app and SigenCloud portal as a four-digit number, where the first digit points to the component: 1000-series = inverter/energy controller, 2000 = battery, 3000 = gateway, 4000 = peripherals, 5000 = EV charger. Most codes also carry a sub-ID (ID1, ID2, etc.) that pinpoints the exact string, phase, or module involved. The list below covers the most common, well-documented 1000-series operational alarms; we have deliberately left out codes we could not verify against authoritative documentation. Safety note: SigenStor combines high-voltage DC strings, a high-voltage battery, and a grid connection in one enclosure. Treat every alarm as live. Do not open the unit, disturb DC isolators or PV/battery wiring, or touch any AC connection — in Australia that is licensed-electrician (and, for grid work, accredited-installer) territory. Where this product carried a safety recall on some single-phase EC models, follow your installer's and Sigenergy's instructions rather than self-servicing. - 1002 — Low insulation resistance (ISO fault): The inverter has measured low insulation resistance on the PV (DC) side — meaning the system is detecting a possible leakage path to earth. Common triggers are moisture ingress in a connector or cable, a damaged DC cable, or a string partially shorting to the protective earth (PE). It often appears in the early morning when humidity is highest and may self-clear as things dry out. — Fix: If it self-clears as the day warms up, it was most likely transient damp. If it persists or recurs, do not start pulling DC plugs apart yourself — the strings can sit at hundreds of volts. Log the code in the mySigen app and have your installer or a licensed electrician inspect the DC cabling, connectors, and earthing. - 1003 — Inverter over-temperature: The inverter has exceeded its safe internal operating temperature and has throttled or shut down to protect itself. Usual causes are high ambient temperature, the unit sitting in direct sun, or restricted airflow/poor ventilation around the tower. — Fix: Make sure nothing is blocking airflow around the unit and that it is not baking in direct afternoon sun (a sail or shade can help on a hot Australian roof or wall). It should resume automatically once it cools. If it keeps tripping in normal conditions, contact your installer — do not open the enclosure. - 1006 — String input overvoltage (PV): The DC voltage from a PV string (the sub-ID identifies which string — e.g. ID1 = String 1) is above the inverter's maximum allowed input voltage. This almost always means too many panels were wired in series for that string, and the problem shows up worst on cold, bright mornings when panel voltage peaks. — Fix: This is a design/wiring issue, not something you can clear from the app. Have your installer review the string sizing and panel count per string against the inverter's maximum input voltage. PV/DC work is licensed-electrician territory — do not rewire strings yourself. - 1009 — AFCI fault (DC arc detected): The arc-fault circuit interrupter has detected what looks like an electrical arc on a PV string (the sub-ID flags which string). This is a genuine fire-safety feature — arcs are usually caused by a damaged DC cable, a loose or corroded connector, or a poor contact at a string terminal. — Fix: Treat this seriously. Note which string (the sub-ID) is flagged. You can attempt one clear/reset via the mySigen app, but if it returns, stop and call your installer — the DC side may have a damaged cable or loose connector that needs a licensed electrician to inspect for burn marks. Do not open connectors on a live string yourself. - 1010 — Grid power outage / grid power failure lock: The inverter has detected that the grid has gone away — either an actual blackout or the AC isolator/main switch being turned off (ID1). A persistent or repeated loss can put the system into a grid-failure lock state (ID2). With backup configured, the system transfers to battery/backup; otherwise it stops exporting and waits. — Fix: Normally informational — the system reconnects on its own once the grid returns. Check whether there is a local blackout or whether an AC switch has been left off. If the grid is clearly present but the alarm stays locked on, have your installer check the AC connection rather than resetting switches yourself. - 1011 — Grid overvoltage (Level I / II / III): The grid voltage at your connection point has risen above the allowed protection threshold, so the inverter disconnects to protect itself and comply with grid rules. Level I is mildest, Level III most severe. This is one of the most common alarms in Australia, especially around midday in areas with lots of rooftop solar pushing voltage up. — Fix: This is almost always a network/grid condition, not a fault in your unit — it should reconnect automatically when voltage settles. If it happens repeatedly and curtails your solar, raise it with your installer and your DNSP (distributor); voltage limits and any volt-watt/volt-var settings should only be changed by your accredited installer. - 1012 — Grid undervoltage (Level I / II / III): The grid voltage has dropped below the protection threshold, so the inverter disconnects until it recovers. It usually reflects a weak or sagging grid supply rather than an inverter fault, and is more common on long rural feeders or during high-demand periods. — Fix: Generally clears by itself once grid voltage recovers. If it persists or happens often, report it to your installer and electricity distributor — there may be a supply-side issue. No user reset of switches or settings. - 1013 — Grid overfrequency (Level I / II / III): The grid frequency has risen above the allowed threshold and the inverter has disconnected per grid protection rules. This is a grid-side condition, not an internal fault, and usually clears within seconds. — Fix: Self-recovers when frequency returns to normal. Persistent or frequent trips should be reported to your installer/distributor. Protection thresholds are set to local grid standards and are not for the owner to change. - 1014 — Grid underfrequency (Level I / II / III): The grid frequency has fallen below the allowed threshold and the inverter has disconnected to comply with grid protection requirements. Like overfrequency, it is a grid-side event that normally clears within seconds. — Fix: Self-recovers once frequency stabilises. If it recurs, report it to your installer and distributor; do not alter protection settings. - 1017 — Leak current out of limit: The inverter has measured residual/leakage current above its safety threshold. It is often transient — caused by damp conditions or a momentary disturbance — and the system typically recovers once the environment settles. — Fix: If it self-clears, it was likely a transient damp-weather event. If it recurs frequently, there may be an insulation or earthing issue on the DC or AC side (moisture ingress, damaged cable, or a faulty RCD) — log it and have your installer or a licensed electrician investigate. Do not open the unit or disturb wiring yourself. - 1018 — Communication fault (4G / CAN / meter / gateway): A communication link inside the system has dropped — for example the 4G/monitoring module (ID1), the battery CAN bus (ID2), the energy meter (ID3), or the gateway (ID4). The sub-ID identifies which link. Monitoring or energy-management features may stop working while it is active even if power flow continues. — Fix: A power-cycle (following your installer's documented procedure) often restores communications. If it keeps recurring, a connector may be loose or a module faulty — have your installer reseat connectors and check the wiring rather than opening the enclosure yourself. - 1022 — EPO / emergency stop activated: The emergency power-off (EPO) input has been triggered — typically because someone pressed the emergency-stop button (or, on some installs, a shutdown command in the mySigen app). The system stays shut down for safety until the EPO is released. — Fix: Confirm it is safe to restart, then release/reset the emergency-stop button (or clear the shutdown in the app) to clear the alarm. If the EPO was pressed because of a genuine emergency (smoke, fire, fault), leave it tripped and contact your installer or emergency services first. - 1023 — Neutral disconnected / abnormal AC wiring: The inverter has detected a problem with the AC wiring — most commonly a neutral conductor that is disconnected or has worked loose inside the inverter (ID1), or otherwise abnormal AC wiring (ID2). A poor neutral connection can be a safety hazard. — Fix: This is an AC wiring issue and must be handled by a licensed electrician — do not attempt to inspect or re-terminate AC wiring yourself. Have your installer power down safely and check the neutral and AC terminations. --- ## Tesla (Powerwall 2 / Powerwall 3 home battery) — fault codes Source: https://solaranalytica.com/tesla-powerwall-alert-codes Tesla's Powerwall doesn't use short numeric fault codes the way many inverters do. Instead, your Tesla app shows plain-language alerts and status notifications — things like "Breaker Open", "Powerwall Inactive", or a low-energy warning during an outage. The library below covers the most common homeowner-facing alerts documented by Tesla for Powerwall 2 and Powerwall 3, with plain-English explanations and what to check. It is reference material to help you understand what your app is telling you, not a repair manual. Safety note: A Powerwall is a high-voltage battery system. You can safely do the surface-level steps below — toggling the Powerwall enable switch, restarting from the app, or reducing your household load. But anything involving switchboard breakers that won't reset, AC/DC isolators, the rapid-shutdown circuit, wiring, or opening any enclosure is licensed-electrician work. Stop immediately and call your installer or Tesla if you see or smell burning, scorching, melted plastic, or any heat damage — do not touch the equipment. - Breaker Open — Powerwall breaker is open / off: The AC circuit breaker that connects your Powerwall to your home is in the open (off) position, so the Powerwall is disconnected and can't charge or store energy. Left like this, the battery can slowly drain its reserve and may eventually need a service visit. — Fix: Find the breaker labelled 'Battery' or 'Powerwall' (often at the bottom of your main switchboard or in the Backup Gateway) and switch it back to on/closed, then follow the app prompt to restart the Powerwall. If the breaker won't stay on, trips repeatedly, or you notice any burning smell, discolouration, or heat damage, do NOT keep resetting it — this is licensed-electrician work; contact your installer or Tesla. - Powerwall Overloaded — Powerwall is overloaded — reduce load: During a grid outage your home is drawing more power than the Powerwall can supply at once (for example several high-draw appliances running together), so Powerwall has stopped supplying power to protect itself. — Fix: Turn off high-power loads such as air conditioners, ovens, kettles, pool pumps, EV charging or instantaneous hot water, then wait. Powerwall automatically retries within about two minutes and should resume powering the home once the load drops; you can also restart it with a quick toggle of its on/off switch. If it keeps overloading with very little running, have your installer review your backup load setup. - Powerwall Inactive — Powerwall has stopped powering the home (inactive): Powerwall has entered an inactive state — commonly after running very low on energy during an outage or after repeated overloads — and is no longer supplying your home. Tesla notes that when low, if the remaining energy decreases by more than about 2.5% it becomes inactive and waits for the next hour to try charging again. — Fix: If your phone is paired to the Powerwall and online, open the Tesla app, tap 'Powerwall Inactive', review the prompt and tap 'Restart Powerwall'. Only restart when there's enough daylight/solar (or grid) available to power the home and recharge the battery. If the app restart fails, you can power-cycle the system per Tesla's instructions; if it still won't come back, contact your installer or Tesla. - Powerwall Low on Energy — Powerwall is low on energy: Battery charge is getting low (typically during a grid outage). Backup time is limited and will run out sooner if your usage stays high. — Fix: Reduce your household power use — switch off non-essential and high-draw appliances — to stretch the remaining backup time until the grid returns or solar recharges the battery. No technical work required. - Powerwall Energy Very Low — Powerwall energy very low — limited backup remaining: The battery is nearly empty during an outage and may fully discharge if usage isn't cut back. Tesla's wording is along the lines of 'Powerwall energy is very low, and you will have limited backup time remaining.' Once it gets too low it stops providing power to protect the cells. — Fix: Immediately reduce your home's power use to the essentials to extend backup duration. If the battery does run out, it will resume during daylight hours once solar provides enough charge. No technical work required. - Powerwall Stopped (Discharged) — Powerwall too low and stopped powering the home: The battery dropped to its minimum and has stopped supplying power to protect the cells. Tesla documents that if an outage occurs while stored energy is below about 5% you immediately lose backup and Powerwall saves the remaining energy to recharge from solar the next morning; separately, once a Powerwall drops below roughly 10% during an outage it enters standby and stops providing power. Either way this is normal protective behaviour, not a fault. — Fix: Wait for recharge — when paired with solar, Powerwall periodically tries to recharge (Tesla cites automatic attempts roughly hourly between about 8am and 4pm) and resumes powering the home during daylight once it has charged enough, or when grid power returns. You can also reduce load so incoming solar goes toward recharging faster. No technical work required. - Rapid Shutdown (RSD) Initiated — Rapid shutdown triggered — Powerwall won't power home: The rapid-shutdown safety circuit has been triggered, so Powerwall will not power your home. Tesla's alert typically reads 'Rapid Shutdown Initiated. Check AC breaker and low-voltage rapid shutdown circuit.' This is a safety function tied to the AC breaker and the low-voltage RSD wiring, not a simple consumer button you reset. — Fix: Check that the relevant AC breaker is on. If that doesn't clear it, leave the system as-is and contact your installer or Tesla — diagnosing the rapid-shutdown circuit (jumpers, low-voltage wiring, any system shutdown switch) is licensed-electrician work. Do not attempt to bypass the rapid-shutdown circuit. - Internal Fault — Replacement Required — Powerwall disabled by an internal fault: Powerwall has been disabled because of an internal hardware fault, and you may see a flashing red logo LED on the unit with an app alert such as 'Powerwall Disabled' or 'Internal Fault Detected'. Powerwall and its components are not user-serviceable — a persistent internal fault means the unit needs professional support or replacement. — Fix: You can attempt a single basic reset per Tesla's instructions (e.g. power-cycling at the breaker for at least 10 seconds). If the logo LED keeps blinking red or the fault persists, turn off the Powerwall enable switch and contact your installer or Tesla. Do not attempt to open or repair the unit. - Arc Fault Lockout — Arc fault detected — system locked out (PV): Powerwall 3 (which has a built-in solar inverter) detected arc faults on the DC solar wiring. Tesla states that five arc-fault alerts within 24 hours triggers an arc-fault lockout. Arc faults are usually caused by damaged insulation, loose or poorly seated DC connectors, or frayed wiring — a genuine fire-safety concern. — Fix: This is not a homeowner fix. Leave the system locked out and contact your installer or Tesla — a qualified person must inspect the DC string connections and wiring (tug-tests, insulation checks, junction boxes, string voltages) before the system is cleared to run again. Do not bypass the lockout. - Going Off-Grid / Grid Outage — Grid is down — running on backup: Status notification (not a fault): the grid has gone down (or you initiated Go Off-Grid) and your home is now running on Powerwall backup. Tesla sends this so you can manage your energy use during the outage. Note that if your internet is also down during an outage, this notification may not arrive. — Fix: No action needed — this is informational. Manage usage to make your backup last (prioritise essentials), and your system will reconnect automatically when the grid returns. - Storm Watch Activated — Storm Watch is active — charging to full: Status notification (not a fault): Tesla's Storm Watch detected a severe-weather forecast in your area (via national weather services) that could cause an outage, so Powerwall is charging to maximum capacity to give you the most backup protection. It stays in Storm Watch until the weather event passes. — Fix: No action needed — this is automatic and informational. Avoid discharging the battery (e.g. heavy loads or EV charging from the battery) if you want it to reach full before any outage. It returns to your normal settings once the weather alert clears. You can opt out in the app if desired. --- # Tools Transparent, in-browser solar calculators — no sign-up, nothing stored. ## Solar System Size Calculator Source: https://solaranalytica.com/solar-system-size-calculator Turn your daily energy use, sun hours and system losses into a recommended array size, panel count and inverter rating. - Converts your daily energy use, sun hours and system losses into a recommended array size in kilowatts. - Also estimates panel count, roof area and an inverter rating to match the array. - Results are estimates that run in your browser, not a quote or engineering specification. ## Solar Payback Calculator Source: https://solaranalytica.com/solar-payback-calculator Estimate annual savings and payback period from system cost, generation, self-consumption, electricity rate and feed-in tariff. - Estimates annual savings and how many years a system takes to pay for itself. - Uses your system cost, generation, self-consumption, electricity rate and feed-in tariff as inputs. - Also projects 10-year and 25-year net positions to show longer-term value. ## Solar Panel Power Density Calculator Source: https://solaranalytica.com/solar-panel-density-calculator From rated power and module dimensions, compute power density in W/m², module efficiency and panels needed per kilowatt. - Computes power density in watts per square metre from a panel's rated power and dimensions. - Also returns module efficiency and how many panels are needed per kilowatt. - Useful for comparing how much power different modules pack into the same area. ## Single or Three-Phase Power? Source: https://solaranalytica.com/single-or-three-phase-power Answer a few questions about your supply and system size to see whether single or three-phase is the right fit — and why it matters for solar. - Helps you see whether single or three-phase power is the right fit for your supply and system size. - Returns a phase recommendation along with the reasoning behind it. - Points you to what to check, so you understand why phase matters for solar. ## Solar Battery Size Calculator Source: https://solaranalytica.com/solar-battery-size-calculator Size a home battery from your overnight energy use, days of autonomy, depth of discharge and round-trip efficiency. - Sizes a home battery from your overnight energy use and how many days of autonomy you want. - Factors in depth of discharge and round-trip efficiency to separate usable from nominal capacity. - Shows the usable and nominal kilowatt-hours and how much of your nightly load is covered. ## Solar STC Rebate Calculator (Australia) Source: https://solaranalytica.com/solar-stc-rebate-calculator Estimate the federal STC incentive on an Australian solar install from system size, your zone rating, deeming years and the STC price. - Estimates the federal STC incentive on an Australian solar install. - Uses your system size, zone rating, deeming years and the STC price as inputs. - Returns the STC count and an estimated rebate value. ## Solar Cable Voltage Drop Calculator Source: https://solaranalytica.com/solar-cable-voltage-drop-calculator Work out voltage drop on a DC string or single-phase AC run from length, current, conductor size and material — checked against AS/NZS guidance. - Works out voltage drop on a DC string or single-phase AC run. - Uses run length, current, conductor size and material as inputs, checked against AS/NZS guidance. - Returns the drop in volts, the drop as a percentage and a pass or flag against limits. ## Tilt & Orientation Yield Estimator Source: https://solaranalytica.com/solar-tilt-orientation-calculator Get an indicative annual-yield figure for a roof from its direction and pitch, relative to an optimally-oriented array. - Gives an indicative annual-yield figure for a roof from its direction and pitch. - Compares your roof to an optimally-oriented array, expressed as a relative yield percentage. - Adds a rating and guidance so you can read the result at a glance. ## Solar String Sizing Calculator Source: https://solaranalytica.com/solar-string-sizing-calculator Work out how many panels can go in series on a string — within the inverter's MPPT window and under the maximum system voltage — using temperature-corrected module voltages. - Cold mornings raise a module's open-circuit voltage, so the coldest expected temperature sets the maximum panels you can safely put in series. - Hot afternoons lower the operating (Vmp) voltage, so the hottest expected temperature sets the minimum string length to stay within the inverter's MPPT window. - The result is a recommended range of modules per string — an estimate to sanity-check a design, not a substitute for a licensed system designer. ## DC:AC Ratio (Inverter Load Ratio) Calculator Source: https://solaranalytica.com/solar-dc-ac-ratio-calculator Check the ratio of array DC capacity to inverter AC rating — the inverter load ratio — and see whether it sits in the typical range or risks clipping. - The DC:AC ratio (inverter load ratio) divides the array's DC capacity by the inverter's AC rating. - Modern systems are commonly oversized on the DC side — ratios around 1.1 to 1.4 — to use the inverter better across the day. - Very high ratios increase clipping, when the array briefly produces more than the inverter can output, so the tool flags ratios worth a closer look. --- # Glossary Source: https://solaranalytica.com/glossary ## Standard Test Conditions (STC) The fixed lab conditions every panel's headline rating is measured at: 1000 W/m² irradiance, 25 °C cell temperature, and an AM1.5 solar spectrum. It standardises comparison between panels but is far sunnier and cooler than a real roof, so STC numbers overstate everyday output. ## NOCT / NMOT (Nominal Operating Cell Temperature) A more realistic test condition than STC: 800 W/m² irradiance, 20 °C ambient air, and 1 m/s wind, with the module open-rack mounted. This drives the cell to roughly 42–45 °C, so the rated power and figures quoted at NOCT/NMOT sit below STC and closer to real operation. NMOT (IEC 61215:2016) and the older NOCT are near-equivalent. ## Temperature coefficient of Pmax How much a panel's power output changes per degree Celsius of cell temperature above (or below) the 25 °C STC reference, expressed in %/°C. It is negative — power falls as cells heat up — so a value closer to zero is better. Typical: about −0.34%/°C for older PERC, ~−0.30%/°C for TOPCon, and −0.24 to −0.27%/°C for HJT. ## Temperature coefficient of Voc How much a panel's open-circuit voltage changes per degree Celsius relative to 25 °C, in %/°C. Voltage rises as cells get colder, so on a frosty morning Voc can climb above its rated value. Installers use this to ensure a cold-weather string never exceeds the inverter's maximum input voltage. ## Light-Induced Degradation (LID) An initial loss of efficiency in crystalline-silicon cells during their first hours-to-weeks of sun exposure, driven mainly by boron-oxygen complexes forming in the silicon (a legacy of oxygen from the Czochralski crystal-growth process). It typically costs roughly 1–3% of output up front; LID-resistant cell types like TOPCon and HJT largely avoid it. ## Potential-Induced Degradation (PID) A power loss caused by stray leakage currents driven by the high voltage difference between the cells and the grounded module frame, which lets ions (notably sodium) migrate to the cell surface and degrade it. It is accelerated by high system voltage, heat, and humidity, and can cost a large share of output if untreated. PID-resistant construction mitigates it. ## Bifaciality factor For a bifacial panel, the ratio of the rear side's STC efficiency to the front side's, expressed as a percentage (typically ~70–90% depending on cell type). It only matters when the rear face actually sees reflected or scattered light, and real-world rear gain is always well below this lab figure because the back never receives equal irradiance. ## Module efficiency The share of incoming sunlight a whole panel converts to electrical power at STC, expressed as a percentage of the 1000 W/m² it receives over its area. Higher efficiency means more watts from the same roof space; mainstream modules today are roughly 20–23%. ## Power tolerance How far an individual panel's actual power may vary from its nameplate rating. A positive-only tolerance (e.g. 0/+5 W) guarantees you never get less than the label; a ± tolerance means some panels ship under-rated. ## PERC Passivated Emitter and Rear Cell — a crystalline-silicon cell design that adds a reflective passivation layer on the cell's back to bounce unabsorbed light back through the silicon, lifting efficiency over older designs. Long the mainstream standard, it is now being displaced by TOPCon and HJT. ## TOPCon Tunnel Oxide Passivated Contact — an n-type silicon cell architecture that adds an ultra-thin oxide layer plus a passivated contact to cut electrical losses at the rear. It offers higher efficiency, a gentler temperature coefficient, and lower degradation than PERC, and is now the dominant mainstream technology. ## HJT (Heterojunction) Heterojunction Technology — a cell that sandwiches crystalline silicon between thin layers of amorphous silicon for excellent surface passivation. It delivers high efficiency, one of the best (closest-to-zero) temperature coefficients, very low degradation, and naturally high bifaciality, typically at a price premium. ## Busbars The thin conductive lines on a cell's surface that collect the current the fine gridlines gather and carry it to the cell interconnects. More, thinner busbars (multi-busbar / MBB designs) shorten the path current travels, reducing resistive losses and shading. ## Maximum Power Point Tracking (MPPT) A control technique in inverters and charge controllers that continuously adjusts the array's operating voltage and current to keep it at the point that yields the most power as irradiance, temperature, and shading change. Multiple independent MPPT inputs let different roof faces or string lengths be optimised separately. ## String inverter A central inverter that converts the combined DC output of one or more series-wired strings of panels into AC. Cost-effective and simple, but because panels in a string share an operating point, shading or mismatch on one panel can drag down the whole string unless optimisers are added. ## Microinverter A small inverter mounted at each individual panel that converts that panel's DC to AC on the spot. This makes each panel independent — so shading or a fault on one barely affects the others — and adds per-panel monitoring, at higher cost than a string inverter. ## Power optimiser A module-level DC-DC device fitted to each panel that conditions its output (performing per-panel MPPT) before sending it to a central string inverter. It captures much of a microinverter's per-panel benefit while keeping a single inverter for the DC-to-AC conversion. ## Hybrid inverter An inverter that manages solar panels and a battery in one unit, handling DC-to-AC conversion plus battery charging and discharging, and (in many models) backup supply during a grid outage. It removes the need for a separate battery inverter. ## Inverter clipping When an array briefly produces more DC power than the inverter's AC rating can convert, the inverter caps output and the excess is lost. A small amount of clipping at peak times is often an acceptable trade-off for a deliberately oversized array that produces more in weaker light. ## DC-to-AC ratio (inverter loading ratio) The ratio of an array's rated DC power to the inverter's AC output rating. It is usually set above 1 (commonly ~1.1–1.25) to keep the inverter working near its efficient range more of the day; too high a ratio increases clipping losses. ## CEC / weighted inverter efficiency A real-world efficiency figure for inverters that averages performance across a range of load levels rather than just the single best point (peak efficiency). Because inverters rarely run flat-out, this weighted number better reflects everyday DC-to-AC conversion losses. ## Depth of Discharge (DoD) The percentage of a battery's total capacity that is drawn down from full. The maximum recommended DoD sets how much of the rated capacity is actually usable — e.g. a 10 kWh battery rated to 90% DoD gives 9 kWh. Shallower discharges generally extend cycle life. ## Usable capacity The energy a battery actually delivers in normal use, in kWh — its total (nominal) capacity multiplied by the allowed depth of discharge. This, not the nameplate capacity, is the number that matters for sizing how much of your home it can run. ## Round-trip efficiency The share of energy put into a battery that you get back out, after charging and discharging losses, expressed as a percentage. Modern lithium home batteries are typically around 90%, so roughly 10% of stored energy is lost in the cycle. ## LiFePO4 (LFP) Lithium iron phosphate — a lithium-ion battery chemistry favoured for home storage for its long cycle life, strong thermal stability and safety, and tolerance of deep discharge, accepting a slightly lower energy density than nickel-based lithium chemistries. ## Cycle life The number of full charge-discharge cycles a battery can perform before its usable capacity falls to a defined threshold (often 70–80% of original). It depends heavily on chemistry, depth of discharge, and temperature, and underpins warranty throughput guarantees. ## C-rate A measure of how fast a battery charges or discharges relative to its capacity: 1C means full capacity delivered in one hour, 0.5C in two hours. It links a battery's energy (kWh) to its continuous power (kW) capability. ## State of Charge (SoC) The battery's current charge level as a percentage of its usable capacity — the battery equivalent of a fuel gauge. It is the complement of depth of discharge at any moment. ## Open-circuit voltage (Voc) The voltage a panel or string produces with no load connected — its maximum voltage. Because it rises in cold weather, Voc (with the Voc temperature coefficient) sets the worst-case high voltage installers must keep below the inverter's limit. ## Short-circuit current (Isc) The current a panel produces when its terminals are directly connected with no load — its maximum current. It scales with irradiance and is used to size conductors, fuses, and the inverter's current limits. ## Maximum power point (Vmp / Imp) The voltage (Vmp) and current (Imp) at which a panel delivers its greatest power under given conditions; their product is the rated power. MPPT keeps the array operating at this point as conditions shift. ## Maximum system voltage The highest DC voltage a panel is certified to withstand within a series string, commonly 1000 V or 1500 V. It caps how many panels can be wired in series, accounting for cold-weather voltage rise. ## Maximum series fuse rating The largest overcurrent-protection fuse rating a panel is rated to tolerate, used to protect parallel strings from reverse fault current. It is a key input when an installer designs string combiner and fusing. ## MC4 connector The de facto industry-standard weatherproof DC connector for joining panels and array wiring, with a locking latch for a secure, IP-rated connection. Only genuinely compatible connectors should be mated, as cross-brand pairings can fail. ## Rapid shutdown A safety function (required by code in many regions) that quickly de-energises the array's DC conductors on the roof when the system or grid is shut off, reducing shock risk for firefighters and responders. It is typically delivered by module-level electronics. ## Tilt and azimuth Tilt is the angle of the panels from horizontal; azimuth is the compass direction they face. Together they set how much sunlight the array captures across the day and year — in the northern hemisphere a roughly equator-facing (south) orientation maximises annual yield. ## IP rating Ingress Protection rating — a two-digit code for how well an enclosure (e.g. a junction box or inverter) resists solids and water. The first digit covers dust, the second water; IP67/IP68 indicates strong protection suitable for outdoor and immersion exposure. ## Mechanical load rating The maximum pressure a panel is certified to withstand, in pascals (Pa), given separately for front/down loads (snow) and rear/uplift loads (wind). It governs allowable mounting and spacing in high-snow or high-wind sites. ## Glass-glass (dual-glass) module A panel with tempered glass on both front and back instead of a polymer backsheet. The symmetric build improves durability, moisture and PID resistance, and supports bifacial operation, usually at extra weight. ## IEC 61215 The international design-qualification and type-approval standard for PV modules: a panel passes a defined battery of stress tests (thermal cycling, humidity, mechanical load, and more) proving it survives real-world conditions. It is a baseline credibility mark, not a performance ranking. ## IEC 61730 The international PV-module safety-qualification standard, covering electrical and fire safety; it includes the module's fire class/rating (often also expressed as a UL 790 Class A–C rating) needed for code compliance and insurance. ## Annual degradation The steady yearly decline in a panel's output after the first year, typically around 0.4–0.55% per year for quality modules. Combined with the larger first-year drop, it determines the end-of-warranty power floor. ## Performance (power) warranty The manufacturer's guarantee that a panel will still produce at least a stated percentage of its rated power after a given period (e.g. ≥87% at year 25), backstopping the degradation curve. It is separate from, and often longer than, the product/workmanship warranty. ## Product (workmanship) warranty The warranty covering manufacturing defects in the panel itself, distinct from the performance warranty. Strong brands offer 25–30 years; the real value depends on whether labour and shipping for replacements are included. ## Performance ratio (PR) A system-quality metric: the ratio of a system's actual AC energy output to the output it would theoretically produce at STC efficiency for the sunlight it received, expressed as a percentage. It nets out losses from heat, wiring, soiling, and conversion, so a higher PR means a tighter installation. ## Specific yield Annual energy produced per unit of installed capacity, in kWh per kWp per year. It normalises output by system size, making it the fair way to compare productivity across systems and locations. ## Capacity factor The ratio of a system's actual energy output over a period to what it would have produced running at full rated power the whole time, as a percentage. For rooftop solar it is modest (often ~10–25%) because the sun is intermittent. ## Soiling loss The output lost when dust, dirt, pollen, bird droppings, or snow accumulate on panel glass and block light. It varies by climate and tilt and is recovered by rain or cleaning; it is one of the loss terms a performance ratio captures. ## Feed-in tariff (FiT) A rate paid to a system owner for surplus solar energy exported to the grid, set per kilowatt-hour. Modern export rates are usually well below the retail import price, which is why self-consumption and batteries have grown more valuable. ## Net metering A billing arrangement that credits exported solar energy against the grid energy you import, effectively letting the meter run backwards. Where offered at full retail value it is highly favourable, but many markets have shifted to lower net-billing export rates. ## Frequency Control Ancillary Services (FCAS) Grid-balancing services (notably in Australia's NEM) procured by AEMO to keep system frequency near 50 Hz by rapidly injecting or absorbing power. Their split-second response makes batteries strong providers of contingency FCAS, creating a revenue stream beyond energy arbitrage. ## Virtual power plant (VPP) A fleet of distributed home batteries (and sometimes other assets) coordinated by software to act as one larger resource, exporting or storing on cue to support the grid. Participating households are typically paid for the flexibility they provide. ## Time-of-use (TOU) tariff An electricity tariff where the per-kWh price varies by time of day (peak, shoulder, off-peak). It rewards shifting consumption — or discharging a battery — into expensive peak windows and charging during cheap periods. ## Self-consumption The share of a system's generated energy used on-site rather than exported. As export rates have fallen below retail prices, maximising self-consumption (often via batteries and load shifting) has become the main driver of solar savings. ## Curtailment The deliberate reduction of a system's output below what it could produce, ordered by the network — for example export limiting that caps how much a home system can push to the grid. It protects grid stability but can waste otherwise available solar energy.