Solar PV Inverter Faults, Error Codes & Repairs
Inverter showing a warning light, fault code or no generation? Mr Solar diagnoses faults on both older and modern solar PV systems, including installations originally fitted by other companies.
Four Faults We See Regularly
Solar inverters are sophisticated power-electronic devices. Some faults originate inside the inverter, while others are caused by the PV array, DC cabling, grid supply or the original installation.
Overheating
Poor ventilation, blocked cooling paths, dust or high ambient temperatures can cause an inverter to reduce power or shut down to protect itself.
Isolation Faults
Moisture, damaged DC cabling, connectors, panel faults or installation defects can create insulation-resistance problems and cause the inverter to stop operating.
MPPT Problems
Maximum Power Point Tracking controls how the inverter extracts power from the solar strings. Abnormal string voltage, current or internal MPPT failure can reduce generation.
Internal Inverter Failure
Relays, capacitors, power electronics, control boards and other components can fail with age, heat and operating hours.
What Can You Check Before Calling Us?
Some information can be gathered safely without opening the inverter or touching any DC connectors.
- Read and photograph the exact error or warning code
- Check whether the inverter display is powered
- Check whether the generation meter is still increasing
- Look for obvious external damage or water ingress
- Check whether an AC breaker has tripped
- Check the monitoring app for the time generation stopped
- Find the inverter model and serial number where accessible
Choose Your Inverter Brand
Many UK solar systems installed from around 2010 onward still use these inverter families. We have dedicated fault-code information for each.
SMA Sunny Boy
SMA Sunny Boy inverters were widely installed across the UK and many remain in service. We can diagnose error codes, isolation faults, relay faults and age-related failures.
SMA fault codes →
Fronius
Fronius inverters use status and error codes to identify grid, DC, communications and internal faults. Our guide explains common messages and next steps.
Fronius fault codes →
Power One Aurora / ABB
Power One Aurora inverters are common on older UK PV installations. Many are now reaching an age where internal errors, including E031-type faults, can occur.
Power One Aurora guide →
Samil SolarRiver
Samil SolarRiver string inverters were fitted on many UK systems. We can help identify common warning codes and advise whether repair or replacement is the sensible option.
Samil SolarRiver guide →We Diagnose Many Other Solar Inverters Too
The four brands above are useful legacy fault-code guides, but our repair work is not limited to them.
We regularly inspect modern string, hybrid and AC-coupled systems and can test the solar array, inverter, protection, metering and communications rather than assuming the inverter itself is always at fault.
From Fault Code to Confirmed Diagnosis
Identify the Fault
We record the make, model, error code and when the system stopped operating normally.
Electrical Testing
Where required, we test the AC supply, DC strings, insulation resistance, protection and related components.
Confirm the Cause
We distinguish between inverter failure and external issues such as cabling, panels, grid conditions or metering.
Repair or Replace
We explain whether repair is practical or whether a modern replacement inverter offers the better long-term solution.
Solar Inverter Fault FAQ
How do I know if my solar inverter has failed?
Typical signs include no generation, a blank display, persistent error codes, red warning lights, repeated tripping or the monitoring system showing zero output when the panels should be generating.
Can I reset the inverter myself?
Some manufacturers publish a safe shutdown and restart procedure for users. Only follow the manufacturer’s instructions and never open the inverter or disconnect live DC connectors.
Does every fault code mean I need a new inverter?
No. Many fault codes relate to grid voltage, insulation resistance, DC strings, communications or temporary operating conditions. Testing should confirm the cause before equipment is replaced.
How long does a solar inverter normally last?
Service life varies substantially by model, environment and loading. Many older string inverters start to experience age-related issues after a number of years, which is why repair versus replacement needs to be considered case by case.
Can you replace an old inverter without replacing my panels?
Often, yes. The existing array first needs to be tested and the replacement inverter must be electrically suitable for the panel strings, voltage, current and existing installation.
Can you repair a system installed by another company?
Yes. Mr Solar investigates existing PV systems regardless of the original installer, including systems where the installer has stopped trading.
Get the fault properly diagnosed before replacing equipment.
Send us the inverter make, model and error code, or arrange a diagnostic visit across Norfolk and Suffolk.