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.