Solis Fault Code Index
Every Solis fault code from the inverter display and SolisCloud portal — what it means, the most likely cause, and what to do. Find your code in the index below or use the category sections to browse by system area.
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If your Solis inverter is showing a fault code and you need expert diagnosis, a remote diagnostic identifies the cause and recommends the fix — usually within 30 minutes.
Book Solis diagnosis — £75 → How diagnostics workFault codes generated by the Solis inverter in response to DC voltage issues, temperature, and hardware failures.
F01 / DC over voltage
PV voltage too high
F02 / DC insulation fault
⚠ Insulation fault
F04 / Over temperature
Temperature too high
F05 / Relay fault
Relay not operating
F07 / AFCI arc fault
⚠ Arc fault
INI-FAULT / Initialisation fault
Startup self-test failed
Grid voltage and frequency events that cause the inverter to disconnect as a safety protection.
F12 / Grid over voltage
Overvoltage disconnect
F13 / Grid under voltage
Undervoltage disconnect
F14 / Grid over frequency
Over-frequency disconnect
F15 / Grid under frequency
Under-frequency disconnect
F16 / Grid lost
No grid supply
G-IMP / Grid impedance high
Grid impedance too high
Fault codes related to insulation resistance on the DC and AC sides of the inverter.
F03 / AC isolation fault
⚠ AC insulation
Fault codes from the battery management system — communication failures and voltage protection events.
F21 / BMS communication fail
BMS not responding
F22 / Battery over voltage
Voltage too high
F23 / Battery under voltage
Voltage too low
F24 / Battery over current
Current exceeded limit
Faults related to data communication between inverter and monitoring portal, and with system components.
Meter comms fail
Meter offline
SolisCloud offline
Portal not receiving data
DRM fault
Demand response mode
Solis releases firmware updates that may introduce new fault codes. If your code isn't listed, share the exact code from your inverter display or SolisCloud and we'll identify it.
Identifying fault source in PV string cabling, connectors, and panel junction boxes.
RS485 cable checks, power cycle, firmware compatibility, and hardware fault diagnosis.
Overvoltage causes, DNO notification process, and export limit configuration.
Solis fault code questions
Solis fault codes appear on the inverter display as an F-code (e.g. F02, F12). They are also logged in the SolisCloud portal under Device > Event Log, and in the SolisCloud app under fault history. Note the exact F-code number and any sub-code shown in brackets — this helps identify whether the fault is persistent or transient.
F02 is a DC insulation fault — the resistance between the PV string DC conductors and earth has dropped below a safe threshold. This is commonly caused by water ingress at MC4 connectors, damaged string cable insulation, or a faulty panel junction box. Do not touch any DC cabling. Isolate the system at the consumer unit and call a qualified engineer to identify and rectify the fault source before restarting.
Recurring grid faults on Solis RHI models are most commonly caused by grid voltage at the property being consistently above 253V — a common issue in areas with high solar density where solar export is pushing local grid voltage up. Check the voltage reading in SolisCloud or on the inverter display. If voltage is consistently above 250V, contact your DNO — they may need to adjust the local transformer tap or apply a lower export limit.
Yes, persistent Solis fault codes may indicate a hardware fault with the inverter, grid relay, or DC input. STS engineers can review your SolisCloud data remotely from £75 and advise whether an on-site repair is needed.
Got a fault code and need it diagnosed?
Share the exact fault code from your inverter display or SolisCloud, what the system is doing, and when it started. We'll identify the cause and tell you whether it needs a remote settings fix or a site visit.