Most solar panels are built to keep working for decades, and many makers warrant their output for around 25 years. They slowly produce a little less each year rather than suddenly stopping. The inverter usually wears out first. Sources: US Department of Energy and Energy Saving Trust.
So the honest answer isn't one number. A panel might still be making useful power long after its warranty ends. What matters is how the whole system ages, and whether it's looked after.
What wears out first
Panels are solid pieces of glass, silicon and metal with no moving parts, which is why they last. The parts around them have a harder life.
- Inverters turn the panels' direct current into the alternating current your home uses. They work hard all day, and many installations need a replacement inverter at some point during the panels' life.
- Connectors and cables sit outdoors in sun, rain and frost. Poor connections are a common source of faults.
- Mounting hardware and roof fixings need to stay secure and watertight through years of wind and weather.
| Component | Typical life, in words | What to check |
|---|---|---|
| Solar panels | Several decades | Cracks, discolouration, falling output |
| String inverter | Shorter than the panels. Often needs replacing once | Warranty length, error lights, app alerts |
| Microinverters | Often warranted for a long period, closer to the panels | Warranty terms, monitoring data |
| Connectors and cables | Long if installed well | Damage, loose or exposed wiring |
| Mounting and roof fixings | Decades if installed well | Movement, rust, signs of leaks |
| Battery (if you have one) | Shorter than panels | Warranty cycles and capacity left |
Degradation in plain English
Panels don't switch off one day. They lose a tiny amount of output each year, called degradation. The first year can show a slightly bigger drop, then it settles into a slow, steady decline. A panel that's old but still working might produce a bit less than it did on day one, and that's normal.
Heat, humidity and the quality of the original build all play a part. The figures vary by maker and model, so look at the datasheet and warranty for the exact numbers on your panels.
What affects how long they last
Two identical panels can age differently, depending on where they live and how they were fitted.
- Climate: strong sun, heat, heavy snow, salty coastal air and hail all put stress on panels and fixings. Panels are tested for tough weather, but harsher places can mean faster wear.
- Installation quality: well-made connections, correct cable routing and secure fixings matter as much as the panels you pick. Many later faults trace back to the fitting, not the panel.
- Panel build: reputable makers publish datasheets and warranty terms. Ask to see them before you buy.
- Roof condition: if your roof needs work soon, sort it before the panels go on, because taking panels off and putting them back is a job in itself.
- Maintenance: a clear, unshaded array with regular checks stays closer to its best output.
That last point is easy to miss. A system nobody looks at can run below its best for months before anyone notices.
It also helps to remember that output varies from day to day anyway. Cloud, season and temperature all change it, so compare like with like, such as the same month across different years, before you decide something is wrong.
Signs your panels need attention
- Your generation drops a lot compared with the same time of year before.
- The inverter shows a fault light or an error code.
- You can see cracks, browning, bubbling or water inside the glass.
- Cables look damaged, or something looks loose on the roof.
- A bird nest or debris has built up under the panels.
- Your monitoring app shows one panel or string behaving differently from the rest.
Don't climb onto the roof to check. Ask a qualified installer, such as an MCS-certified one in the UK, or a licensed installer where you live.
Keeping them working
- Cleaning: rain does most of the job. If you need more, follow the maker's guidance and avoid harsh scrubbing or a pressure washer.
- Shading: trees grow. A branch that wasn't a problem when the system went in may be one now.
- Installer checks: a visit every so often to inspect connections, the inverter and the fixings can catch small faults early.
- Monitoring: check your generation figures now and then, so a drop shows up quickly.
- If you run a business and want to cut energy bills, I've written about sustainability upgrades that can save money. And if you work in solar and want to share what you know, here's how to write for my solar section.
Warranties: product vs performance
Most panels come with two kinds of warranty, and they cover different things.
- A product warranty covers defects in the panel itself, such as faulty materials or workmanship. It's usually shorter.
- A performance warranty promises that the panel will still produce a stated minimum of its original output after a set number of years. It's usually longer, and it's where the 25-year figure comes from.
Read both. Check who honours the claim, whether you need to prove the fault, and what happens if the installer goes out of business. Inverters have their own, separate warranty.
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Keep your paperwork somewhere safe. Installation certificates, the datasheets and the warranty documents are what you'll need if you ever make a claim or sell the property, and a buyer will often ask to see them.
What happens at the end
When panels do reach the end of their working life, they shouldn't go in the bin. Panels contain glass, aluminium and other materials that can be recycled. In the UK and the EU, solar panels are covered by waste electrical equipment rules, and there are take-back and recycling schemes. In the US, requirements vary by state, so ask your installer or local waste authority what's available.
If you're replacing a system early, ask your installer whether the old panels can be reused elsewhere or sent for recycling. Some installers will take them away as part of the job, but it's worth asking before the work starts.
Some older panels also find a second life on sheds, outbuildings or off-grid projects, as long as they're tested and still safe.
Frequently asked questions
How long do solar panels last?
Most are built to work for decades, and many makers warrant their output for around 25 years. They lose a little output each year rather than stopping suddenly.
Do solar panels stop working after 25 years?
No. The warranty period isn't a cut-off date. Panels often keep producing power beyond it, just at a somewhat lower level than when they were new.
What is the weakest part of a solar system?
Usually the inverter, which commonly needs replacing once during the panels' life. Check its warranty and ask your installer what to expect.
Can I recycle old solar panels?
Yes. Panels contain materials that can be recycled, and schemes exist in the UK and EU. In the US, options vary by state, so ask your installer or local waste authority.
