Servicing · Guide
How long do solar panels last?
The short answer: 25 years or more. That’s the Energy Saving Trust’s figure, and it matches what we see on roofs. Plenty of systems fitted in the early feed-in tariff years are still generating well.
Mon–Fri 9:00am–5:00pm · Clear written quote before any work starts
Talk to us about solar, batteries or repairs.
Call 0800 156 0191, Monday to Friday, 9:00am–5:00pm, or send us a message through our contact page.
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Degradation
How much output do panels lose each year?
The longer answer is that a solar system is more than its panels. The inverter, isolators, connectors, cables and roof fixings all have shorter lives than the glass. How long your system keeps earning depends mostly on how those parts are looked after.
Panels don’t stop working at a set age. They slowly produce a little less each year.
A review by the US National Renewable Energy Laboratory looked at around 2,000 measured degradation rates from systems around the world. It found a median loss of about 0.5% a year. At that rate, a healthy panel is still producing about 90% of its original output after 20 years.
That gives you a useful yardstick. A system losing a fraction of a percent a year is ageing normally. A system whose yearly total has dropped by 10% or 20% since last year has a fault, not old age.
Wear and tear
What wears out first.
In roughly the order we see it:
- The inverter. It converts the panels’ DC power into AC for your home. The Energy Saving Trust says to expect to replace it after around 12 years, and most systems will need at least one replacement in the panels’ lifetime. See how long do solar inverters last?
- Isolators and connectors. They sit outside or in lofts through every winter. Water getting into an isolator, or a DC connector that has worked loose, can trip the system or overheat.
- Surge protectors and fuses, where fitted. They are designed to sacrifice themselves, so once they have done their job they need replacing.
- Cables and fixings. Sunlight, wind and roof movement take their toll on cable ties, clips and clamps, especially after storms.
- The panels themselves. When a panel does fail, it’s usually from cracked glass, a hot spot, water getting in, or a fault in the junction box on its back, rather than from age.
Birds speed all of this up. Pigeons nesting under an array chew cables and leave mess that holds damp against connectors. See solar panel bird proofing.
Ageing or fault
How to tell ageing from a fault.
- Compare like with like. Read your generation meter on the same date each year, or compare the same month year on year in your app. Don’t compare December with June.
- Small, steady drops are normal. A fraction of a percent a year is expected.
- Sudden or large drops aren’t. A big fall between one year and the next, or zero on a bright day, means something has failed. The usual culprits are the inverter, a tripped circuit, or one string of panels that has stopped contributing.
If the numbers don’t look right, see solar panel repair, or book a check and we’ll test each circuit and tell you where the loss is.
Looking after it
How to make a system last longer.
- Have it serviced. A yearly check finds water in isolators, loose connectors and failing inverters early. See solar panel maintenance for the 21 checks we make.
- Give the inverter room to breathe. Heat shortens inverter life, so keep vents clear and don’t stack boxes around it in the loft or garage.
- Keep trees trimmed, and deal with pigeons before they nest.
- Fix small faults quickly. A system that trips now and then is telling you something, and the cause usually gets worse.
After 25 years
What happens after 25 years?
Nothing dramatic. Panels don’t switch off on their 25th birthday; they carry on generating at a slightly lower output.
- Feed-in tariff payments run for 20 or 25 years depending on when your system was registered. That means the oldest systems reach the end of their payments from 2035 onwards, but they still save you money on every unit you use at home. See feed-in tariff meter readings.
- Replacing single panels. If a panel fails on an older system, it can often be replaced on its own. Exact matches may no longer be made, so the replacement has to be chosen to suit the rest of its string. See replacing a single solar panel.
- When the inverter fails late in the system’s life, it’s often the right moment to fit a hybrid inverter and add battery storage.
You get a clear written quote before any work starts, and we’ll tell you if repairing isn’t worth it.
Sources: Energy Saving Trust, Solar panels: costs, savings and benefits explained (updated August 2026); Jordan and Kurtz, Photovoltaic Degradation Rates: An Analytical Review (NREL).
A yearly clean and service is the simplest way to keep a system going. Our Solar Maintenance Plans include both, with every visit report kept in your My Solar account.
Questions
The things people ask before they ring.
Not answered here? Call 0800 156 0191, Monday to Friday, 9:00am–5:00pm.
Do solar panels stop working after 25 years?
No. Twenty-five years is roughly the life manufacturers design panels for, but they keep generating after that, just at a gradually lower output. A healthy panel losing around half a percent a year is still producing most of its original output at 25 years.
How much output do solar panels lose each year?
Typically about 0.5% a year, according to a large review of measured degradation rates by the US National Renewable Energy Laboratory. A much bigger drop than that from one year to the next points to a fault rather than ageing.
Is it worth repairing an old solar system?
Usually, yes. The most common fault on an older system is a failed inverter. Replacing it gets the whole array generating again without touching the panels. We’ll check the panels and wiring too, and give you a clear written quote before any work starts.
Can one broken solar panel be replaced?
Often, yes. A cracked or failed panel can usually be swapped on its own. On older systems the original model may no longer be made, so the replacement has to be matched to the rest of its string. We check this before quoting.
Ready when you are
Not sure if your system is ageing normally?
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.