Solar PV and Panel Repairs UK: Faults and Safety
A fall in solar generation does not always mean the panels have failed. Monitoring, grid supply, an inverter, isolator, connector, cable, shade, dirt or a battery setting can all affect the result. Start with safe observations and use a competent solar or electrical professional for testing and repair.
Solar fault checker
Choose the closest sign below. This cannot diagnose an electrical fault, but it can help you decide how urgent it is, what to record and who to contact.
Safety basis: Electrical Safety First solar guidance and RECC guidance for faulty or underperforming systems.
Do not dismantle or test rooftop DC equipment
Solar panels can produce direct-current electricity whenever light reaches them, even if household power is switched off. Do not open an inverter, unplug rooftop connectors, remove panel covers or climb onto the roof. Do not repeatedly reset an error unless the manufacturer or a competent professional has confirmed that action is safe.
Safe checks from ground level
- Check whether the monitoring app is offline or whether generation itself is zero.
- Record the date, weather, displayed power, daily kWh and exact inverter or battery error code.
- Compare with the same season and similar weather rather than one unusually sunny day.
- Check for a known local grid outage.
- From the ground, look for new shade, heavy debris, visible cracked glass or obvious cable damage.
- Find the handover pack, system diagram, warranties, MCS certificate and installer details.
Common symptoms and sensible next actions
| Symptom | Possible area | Next action |
|---|---|---|
| Monitoring app says offline but inverter looks normal | Router, Wi-Fi, data logger or portal | Check the app provider’s status and documented connection steps before assuming generation has failed. |
| Inverter display is blank | Supply, isolator, inverter or wiring | Photograph the state and contact the installer or qualified repairer; do not open equipment. |
| Specific inverter error code | Grid, insulation, string, temperature or internal fault | Record the exact code and model, then use the manufacturer’s support route or a qualified engineer. |
| Generation is lower than previous years | Shade, soiling, string fault, degradation, meter or model comparison | Compare like-for-like weather and seasons; request measured string and inverter diagnostics if the difference remains material. |
| One panel appears damaged | Glass, frame, connector or module electronics | Keep clear and arrange a professional inspection, especially after impact or storm damage. |
| Battery not charging or discharging | Settings, reserve level, tariff schedule, communication or battery/inverter fault | Save screenshots of state of charge and settings; contact the system support route. |
| Breaker trips, burning smell or abnormal heat | Potential electrical fault | Treat as urgent; keep away and contact a competent electrician or emergency services as appropriate. |
Low output is not automatically a panel fault
Cloud, seasonal daylight, higher panel temperature, new shade and household consumption can change what an app reports. Compare generation at the inverter or meter with historic generation, not only grid export. Export can fall because the home used more solar directly.
Cleaning and visual maintenance
Most tilted panels receive some cleaning from rain. Heavy deposits, leaves, lichen or bird fouling can reduce output and create uneven heating. Use a specialist where cleaning is genuinely needed; working at height and handling equipment around live generation are not routine DIY jobs.
Electrical Safety First recommends regular visual checks for cracks, loose connections and cable damage, and professional attention when problems appear. Its consumer guidance also recommends regular inspection and testing of the PV system.
Check warranties before approving work
- Installer workmanship warranty.
- Panel product warranty and separate performance warranty.
- Inverter, optimiser, microinverter and battery warranties.
- Insurance-backed guarantee or consumer-code protection.
- Monitoring subscription or communications warranty.
Ask the repairer whether diagnostics or replacement could affect an existing warranty. Do not let a cold caller replace working equipment without a documented fault and written justification.
If the original installer has stopped trading
Contact the equipment manufacturer and any insurance-backed guarantee provider named in the handover documents. Use the MCS directory to find appropriately certified installers, and explain that the job is inspection or remedial work on an existing system. Certification for new installations does not by itself prove experience with every legacy inverter or battery.
Questions for a solar repair company
- Which qualifications and registrations cover this diagnostic work?
- Will you test the AC side, DC strings, insulation and generation evidence as applicable?
- Will I receive a written fault report, test results and photographs?
- Is the proposed part compatible with the existing array, inverter and monitoring?
- Does changing inverter capacity or export control require DNO paperwork?
- What warranty applies to the replacement part and labour?
- What is the diagnostic charge if no fault is found?
After the repair
Keep the fault report, test results, new serial numbers, warranty, invoice, updated schematic and any DNO correspondence with the original handover pack. Confirm that monitoring, export measurement and battery schedules still work.
Related guides
Shareable visual summary
Use this graphic in a relevant article, community resource, presentation or social post. Please keep the wording intact and include visible credit with a link to this guide.
Solar panel repair safety checklist
Usage note: You may use this image if you credit and link to this page.
Suggested attribution: Here4Solar.uk - https://here4solar.uk/solar-panel-repairs/
Suggested attribution
Source: Here4Solar.uk - https://here4solar.uk/solar-panel-repairs/