Repairs · Guide
Solar panels not working? Seven checks to make first
Most solar faults come down to a handful of causes, and several of them you can spot yourself in ten minutes without going near the roof. Work through these checks in order.
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Safety
Safety first.
If the system still isn’t generating afterwards, you’ll have exactly the information an engineer needs.
- Don’t go on the roof, and don’t touch the panels, the cables running from them, or any junction box.
- Solar panels produce electricity whenever there’s daylight. The DC side of the system stays live even when the fuse board is switched off.
- Burning smell, smoke, scorch marks or a crackling sound: keep clear. Follow the emergency shutdown procedure on the label near your inverter only if it is safe to do so, then call an engineer. If there is any sign of fire, call 999.
Check 1
Is there enough light?
Inverters switch off automatically at dawn and dusk and in very dull weather, and switch back on when there’s enough light. Check the system around midday on a reasonably bright day before deciding it has stopped.
In winter, generation is naturally low. See do solar panels work in winter?
Check 2
Look at the inverter.
The inverter is the box that turns the panels’ power into electricity for your home. It’s usually in the loft, garage, utility room or on an outside wall.
- Green light or a normal display: it is running.
- Red or amber light, or an error code: it has found a fault. Write down the code and the make.
- Blank screen in daylight: it has no power from the panels or the grid, or it has failed.
- Clicking on and off repeatedly, or beeping: it is trying to connect and failing.
We explain common codes for SolarEdge, Fronius, SMA, Growatt, Solis and SolaX.
Check 3
Check the fuse board.
Find the breaker or RCD labelled “solar”, “PV” or “inverter” in your consumer unit.
- If it has tripped, you can switch it back on once.
- If it trips again, leave it off and call an engineer. A breaker that keeps tripping is protecting you from a real fault.
Check 4
Check the isolator switches.
Most systems have an AC isolator (a red-and-yellow rotary switch) near the inverter or fuse board, and many have a DC isolator next to the inverter too. Electricians, roofers and meter fitters sometimes turn them off and forget to switch them back on.
- If they are off: switch them back on only by following the start-up order on your system’s label or in the inverter manual.
- If you see water inside the clear cover, or signs of burning: leave them alone and call us. Solar panel isolator switches explains what each switch does.
Check 5
Read the generation meter.
The generation meter records every unit your panels have ever produced. It’s usually next to the inverter or the fuse board.
- Note the reading, then check again a few hours later on a bright day.
- If the number hasn’t moved, the system isn’t generating.
- If it has moved but less than you’d expect, compare with the same month last year.
Check 6
Don’t confuse the app with the panels.
If your monitoring app shows the system as offline or at zero, check the inverter itself before assuming a fault. A new router, a changed Wi-Fi password or a power cut often disconnects the monitoring while the panels carry on generating normally.
Check 7
Look up at the roof from the ground.
From the garden or the street, look for:
- slipped or cracked panels, or storm damage;
- a new shadow from a tree, extension or neighbouring building;
- pigeons nesting under the array, which can chew through cables. See bird proofing.
Common faults
What the common faults usually are.
- Inverter blank in daylight: Tripped breaker or isolator; failed inverter; DC isolator off
- Red light or error code, no generation: Inverter fault; earth or insulation fault on the DC side; grid voltage outside limits
- Fault in the morning that clears by lunchtime: Damp in a DC connector or isolator, often picked up by the inverter’s insulation test
- Trips off on sunny afternoons: Local grid voltage running high, so the inverter disconnects to protect the network
- Working, but much lower output than last year: One string of panels not contributing; a failed optimiser or panel; shading; heavy dirt
- App offline, inverter green: Wi-Fi or monitoring problem, not a generation fault
- Stopped after a storm or power cut: Breaker tripped; isolator damaged or wet; surge protector done its job
Several of these, such as insulation faults and grid voltage problems, need test equipment to confirm. Guessing and resetting repeatedly can make them worse.
Getting help
When to call an engineer.
Call an engineer:
- if the checks above don’t get the system generating again;
- if a fault code keeps coming back or a breaker keeps tripping;
- whenever there is water, damage or scorching.
Our engineers repair systems fitted by any installer, including installers who are no longer trading. We cover England, Wales and Scotland, with same-week inverter repair or replacement. You get a clear written quote before any work starts.
Tell us what you’ve found in the fault finder and it goes straight to our office. See also solar panel repair and inverter repair.
Questions
The things people ask before they ring.
Not answered here? Call 0800 156 0191, Monday to Friday, 9:00am–5:00pm.
Why is my solar inverter showing a red light?
A red or amber light means the inverter has detected a fault and stopped exporting power. Common causes are an insulation or earth fault on the panel side, grid voltage outside its limits, or an internal inverter fault. Note the error code shown on the display or in the app. It usually tells an engineer where to start.
Why have my solar panels stopped working after a power cut?
After a power cut the inverter waits a short time and then reconnects automatically. If it doesn’t, check whether the solar breaker or RCD in the fuse board has tripped. If it trips again when you reset it, leave it off and call an engineer.
How do I know if it’s the panels or the inverter?
If the inverter is blank or showing a fault, the problem is usually the inverter or something between it and the panels, not the panels themselves. If the inverter is running but output is well down on last year, one string of panels, an optimiser or a single panel may have failed. An engineer can test each circuit to find out.
Will you fix solar panels another company installed?
Yes. We repair and service systems fitted by any installer, on any make of panel, inverter or battery, including systems whose original installer has stopped trading.
Ready when you are
Still not working? Let’s find the fault.
We’ll call you back to talk it through, and you get a clear written quote before any work starts. Mon–Fri 9:00am–5:00pm.