SolaX Inverter Error Codes
Common SolaX string and hybrid inverter fault codes explained, with likely causes and what to check.
- Manufacturer
- SolaX Power (X1 / X3 string and hybrid inverters)
- Codes documented
- 30
- Source
- Manufacturer documentation
- Scope
- Reference only
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.
- 30 SolaX Power (X1 / X3 string and hybrid inverters) fault and alarm codes, documented in plain English.
- Compiled from manufacturer documentation — independent and not affiliated with SolaX Power (X1 / X3 string and hybrid inverters).
- Codes involving DC/AC isolators, wiring or opening the unit are licensed-electrician work — when in doubt, call your installer.
30 of 30 codes
- 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.
What to do
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.
What to do
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.)
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
What to do
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.
Sources
- SolaX Power Knowledge Base — Grid Lost Fault (official)
- SolaX Power Help Center — What is Grid Relay Fault and how can I solve it? (official)
- SolaX Power Help Center — How to fix grid lost fault (official)
- SolaX X3-Hybrid G4 Series User Manual (official PDF)
- SolaX X1-Hybrid G4 Series User Manual (official PDF)
- Solair Electrical — SolaX Inverter Fault and Error Codes
- SAE Group — SolaX Solar Inverter Fault Messages
- Gold Coast Solar Power Solutions — SolaX Solar Inverter Fault Messages
Frequently asked
- Where do these SolaX fault codes come from?
- We compile them from publicly available SolaX inverter documentation and field references, then rewrite each entry in plain English. Solar Analytica is independent and not affiliated with SolaX.
- Can I clear these faults myself?
- Some clear automatically once conditions return to normal. 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.
- My exact code isn't listed — why not?
- Firmware and model variants differ, and manufacturers occasionally revise their codes. We document the most common ones; if yours isn't here, check your inverter's manual or ask your installer.
- How current is this reference?
- Last reviewed June 2026. We revise it when the underlying manufacturer documentation changes.
Other inverter fault libraries
Inverter Fault Library
Huawei Inverter Error Codes
Major and minor alarm codes for Huawei SUN2000 residential and commercial inverters, with plain-English causes and field-tested fixes.
Inverter Fault Library
Sungrow Alarm Codes
The complete Sungrow fault reference — string, SH hybrid and battery families — with every alarm number searchable and grouped by root cause.
Inverter Fault Library
Solis Alarm Codes
Solis (Ginlong) inverter alarm codes covering grid, insulation, temperature and hardware faults, with diagnostic next steps.