How long do solar panels last?
Solar panels outlast almost everything else you'll fit to your house. They keep generating for 25 to 30 years or more, fading so slowly that they still produce most of their original output decades in. That long, predictable life is what makes the lifetime maths work, because the savings keep coming for years after the system has paid for itself. Here's how long each part really lasts and what the warranties actually promise.
The panels: 25 to 30+ years
The panels themselves have no moving parts and degrade gently rather than failing suddenly. They lose a small amount of output in the first year, then around 0.5% a year after that. The practical result is that a panel still produces roughly 87% of its original output at 25 years, and most keep going well beyond that at slightly reduced capacity. "End of warranty" is not "stops working."
What the warranties actually mean
Solar panels come with two separate warranties, and it's worth knowing the difference:
- Product warranty. Covers defects in the panel itself, typically 10 to 25 years depending on the brand.
- Performance warranty. Guarantees the panel will still produce at least a stated percentage of its original output after 25 years, commonly around 87 to 92%.
So a "25-year warranty" usually refers to the performance guarantee. The better brands offer longer product warranties too, which is one of the things to compare when reading a quote, as in how to read a solar quote.
Component lifespans at a glance
The panels last longest; other parts have their own timelines.
| Component | Typical lifespan |
|---|---|
| Panels | 25 to 30+ years, fading ~0.5% a year |
| String inverter | 10 to 15 years (one replacement likely) |
| Microinverters / optimisers | Often 20 to 25 years (longer warranties) |
| Battery (if fitted) | ~10 years or ~6,000 cycles |
| Mounting and wiring | The life of the system |
The inverter is the one you'll likely replace once, the planned cost covered in solar panel maintenance. A battery, if you have one, is on a shorter clock, as set out in are solar batteries worth it.
Why slow degradation matters for the maths
Because panels fade so gradually, the bulk of their output happens long after payback. A system that breaks even around year ten then spends 15-plus years in profit, producing power at progressively higher grid prices. This is why the figure that matters is the 25-year net benefit, not the sticker price, the point at the heart of solar panel payback. A panel making 87% at 25 years is still saving you real money every sunny day.
What actually shortens a system's life
Genuine early failures are rare and usually trace back to a poor install rather than the panels: water ingress from bad flashing, undersized or cheap inverters, or loose connections. It's another reason the installer matters more than the brand of panel, covered in how to choose a solar installer. Quality kit, fitted properly under MCS standards, is what delivers the full lifespan.
The detail most people miss
The performance warranty is only as good as the company standing behind it. A 25-year guarantee from a manufacturer that may not exist in 25 years is worth less than a slightly shorter one from an established firm with a UK presence. When comparing panels, look at the warranty terms and the maker's track record together, not the headline number alone. The same logic applies to the installer's own workmanship guarantee, ideally insurance-backed so it survives them.
Frequently asked questions
Yes, but slowly: a small first-year drop, then about 0.5% a year. They still produce roughly 87% of their original output at 25 years and keep going beyond that.
A string inverter typically lasts 10 to 15 years, so expect one replacement over the system's life. Microinverters and optimisers often last longer and carry longer warranties.
A guarantee that the panel will still produce at least a set percentage of its original output, often around 87 to 92%, after 25 years. It's separate from the product warranty covering defects.
No. 25 years is usually the performance-warranty point, not the end of life. Panels keep generating beyond that, just at gradually reduced output.