If your solar inverter isn’t working, don’t order a replacement based on a blank screen or an app showing zero. First check when the reading was taken, whether the monitoring is up to date and whether the system is actually generating. Those three details help separate a communications problem from a fault that needs an engineer.
You don’t need to take anything apart. The useful checks below are observations you can make safely, followed by the information to send an installer if the problem persists.
Stop here if there are signs of damage
Smoke, a burning smell, sparking, exposed wiring or water entering electrical equipment are not routine troubleshooting issues. Keep away and arrange urgent professional help; if there is fire or immediate danger, leave the area and call 999. Do not remove covers, unplug solar connectors, test live wiring or repeatedly reset a tripping circuit.
Only look at equipment you can reach safely without climbing or touching damaged parts. The Energy Saving Trust’s maintenance guidance says damaged cabling presents an electric-shock hazard and should be reported to the installer.
A dark inverter at night may be doing exactly what it should
A conventional solar-only inverter needs sufficient input from the panels before it can generate. A blank display or standby message after sunset is therefore different from the same behaviour on a bright afternoon. Battery and hybrid equipment may remain active overnight, so check the manual for your particular model.
Low light can also delay starting. SMA’s explanation of low-irradiation messages describes how insufficient sunlight, including snow-covered panels, can leave certain models waiting for suitable conditions. Its message numbers apply to the equipment listed, not to every inverter.
Note the time and weather. If the inverter repeatedly stays off through usable daylight, or stops part-way through otherwise normal days, save those observations for an engineer. Don’t dismiss a persistent fault as “just the weather”.
Check whether the app has stopped updating
Open the monitoring app and look for its latest update time. A graph ending yesterday, an offline message or a sudden data gap after a broadband change points towards a connection issue worth checking. It doesn’t establish whether the panels have stopped producing.
Look at the inverter’s accessible display or user interface, if it has one. Does it show current production while the app is offline? Solis’s datalogger guidance treats missing cloud data and internet connectivity as monitoring problems to investigate separately. Follow the owner instructions for your exact logger; there is no need to disconnect equipment to collect useful information.
Check whether your home internet is working and whether the router or Wi-Fi password has changed. Tell your installer what changed and when. A connection problem and an electrical fault can also happen together, so an offline label alone isn’t a diagnosis.
Use generation readings, not just your electricity bill
Where you have a separate generation meter, photograph its total reading and the time. On a conventional PV-only installation, a later increase during daylight is evidence that energy is being recorded. For example, a rise from 12,450.2 to 12,451.0 kWh means 0.8 kWh has been recorded between readings. This is illustrative arithmetic, not a performance target.
Battery systems and more complex metering arrangements need interpretation, so send the readings rather than assuming what each meter measures. Remember that kW is power at a particular moment; kWh is energy accumulated over time.
A higher bill isn’t enough to identify an inverter fault: household use and prices may have changed. Equally, no export doesn’t mean no generation. Your home could be using the solar electricity as it is produced, or a battery could be charging.
An error code is a clue, not a replacement order
Photograph the exact message, including any number, rather than describing it only as a red light. Note whether it appears continuously, at lunchtime, after rain or when particular equipment runs. Warning colours and codes differ between manufacturers and models.
A grid-related warning can require checks outside the inverter itself. UK Power Networks explains that voltage fluctuations can affect solar equipment. Your installer can assess the installation and involve your local network operator where necessary.
Don’t alter grid-protection settings to make an alarm disappear. Likewise, a reset sequence copied from another brand’s video may be unsuitable. Use only the documented owner procedure for your system, or ask the installer first.
When does repair or replacement make sense?
Diagnosis should come before the purchase decision. A problem with monitoring, wiring, an isolator, the array or the incoming supply won’t necessarily be cured by a new inverter. Electrical testing helps establish where the fault is and what work is justified.
Our solar servicing and maintenance service covers investigating system condition and identifying remedial work. Ask what the initial visit includes, whether roof access is needed and whether further investigation would be quoted separately.
If the inverter itself has failed, compare the repair route with a compatible replacement. Check the existing warranty before authorising work: parts, labour, carriage and removal or refitting may have different cover. Age, parts availability, the nature of the fault and the warranty offered on the remedy all matter.
A replacement must suit the existing panel strings and electrical installation, not just have a similar kW label. Sunergy’s solar inverter replacement service can assess the equipment required. Ask for a quote that makes the installation scope and any additional work clear.
Three questions worth asking before you book
Will replacing the inverter affect my Feed-in Tariff?
Replacement does not automatically end FIT accreditation. Ofgem’s guidance for FIT generators, checked on 16 September 2026, allows generating equipment to be repaired or replaced provided the installation continues to meet the scheme rules. Contact your FIT licensee about the proposed change and required records, particularly if capacity or metering will change. Keep the old and new equipment details and relevant readings.
Does a failed inverter mean I need new solar panels?
Not necessarily. The panels and inverter are separate parts of the system. Testing should establish their condition and whether a compatible inverter can work with the existing array. Don’t accept a whole-system replacement as the default without an explanation of why it is needed.
Should I add a battery while replacing the inverter?
It is worth discussing if storage was already in your plans, but it is a separate buying decision. Ask whether the proposed equipment supports a suitable battery and compare the extra cost with your likely use. Our guide to adding battery storage to existing solar outlines the options. You do not have to add storage simply to restore solar generation.
Send us the details that help
For an inverter problem in Nuneaton, Warwickshire, Leicester, Leicestershire or the wider Midlands, send Sunergy:
- Your postcode and the inverter make and model.
- A clear photo of the display or fault message, taken safely.
- When the problem started and whether it is constant or intermittent.
- The app’s last update time and any available generation readings.
- The installation date, warranty information and whether you receive FIT payments.
Contact Sunergy about your inverter fault or call 02477 752 574. We can discuss the next appropriate check and whether a diagnostic visit or replacement assessment is needed.
