Solar panel repairs: what usually goes wrong (and what it costs to fix)

Solar panels themselves are remarkably durable — they’re glass and silicon with no moving parts, and they usually outlast everything around them. So when a system stops performing, the fault is almost always in the kit that supports the panels, not the panels themselves. Here’s what actually goes wrong, and what it tends to cost to put right.

The short answer

Most solar faults sit around the inverter, the isolators, the wiring connections, or the monitoring that tells you the system is working. These are repairable, and a repair is usually far cheaper than replacing a whole system. The catch is finding an installer willing to work on a system they didn’t fit — which is where a lot of people get stuck.

What usually goes wrong

• The inverter. The inverter converts the panels’ DC electricity into the AC your building uses. It works hard, and it’s the component most likely to fault or fail over a system’s life. Error codes and a drop in generation often point here.
• Isolators and connections. DC and AC isolators, and the connections between components, can degrade or work loose. A single poor connection can quietly cost you generation.
• Monitoring. Sometimes the system is generating fine but the app or monitoring has dropped out, so it looks broken when it isn’t — or genuinely has stopped and nobody noticed because the monitoring was never set up.

We cover this work on our solar repairs and servicing page, and a regular service catches most of these before they cost you anything. For general guidance on wiring standards behind this kind of work, the IET is the authoritative body, and the Energy Saving Trust covers solar maintenance in plain terms.

Why it’s rarely the panels

People assume a drop in output means a dead panel, but panels degrade slowly and predictably over decades. A sudden change is far more likely to be an inverter fault, a tripped isolator or a failed connection. That matters because the fix is completely different — and much cheaper — than replacing panels. Diagnosing properly, rather than assuming, is the whole game. It also means you’re never sold a new system you didn’t need.

Inherited a system with no paperwork?

This is one of the most common reasons people call us. One customer bought a house with solar already fitted and could get no help from the original company — no battery schematics, no way to update the monitoring app to their details. We produced the schematics, spent the hours it took to work through it with the manufacturers, registered the system in their name and got it running properly. If you’ve taken on a system you know nothing about, that’s a solvable problem.

Repair or replace?

The solar industry has a repair problem: almost every installer would rather sell you a new system than fix the one you have. We take the opposite view. A repair to an inverter or a connection is a fraction of the cost of a replacement and gets you back to full generation, and we’ll tell you honestly when that’s the right call — and the rare times when it genuinely isn’t.

If your system isn’t doing what it should, start an enquiry and we’ll find out why. You can also read how we approach solar and battery installs from scratch.