Solar panel lifespan, degradation and warranties How long do solar panels last?

How much output solar panels lose each year

Panels don't suddenly stop. They lose a little output each year, which is called degradation. Datasheets for modern panels typically allow about 1% in the first year, then 0.25% to 0.4% a year after that, depending on the technology.

To put that in years: on Trina's terms (1% in year one, then no more than 0.4% a year), a panel should still make at least 95.4% of its rated output after ten years, 89.4% after 25 and 87.4% after 30. These are minimum guarantees, so a panel bought today should still make well over 80% of its original output after 25 to 30 years.

How to monitor performance and look after them

You don't need to do much. Panels have no moving parts, and care is mostly a matter of checking them now and then and spotting faults early. On a pitched roof, rain does most of the cleaning: the Energy Saving Trust says it keeps panels tilted at 15 degrees or more clean in the UK. Dirt only matters when it builds up, because it cuts how much light reaches the cells.

Checks and cleaning

• Check the panels every 12 to 18 months, and clean them only if there's visible dirt.
• Clean from the ground if you can, or get a professional. Don't climb on the roof or stand on the panels, which can crack.
• Turn the system off first. Use plain water, not washing-up liquid, which can leave a residue, and never a power washer.
• Every one to two years, look over the panels, mounting system and any visible wiring for damage, water getting in, dirt build-up, bird droppings or lichen.
• Every three to five years, the Energy Saving Trust suggests a full professional service to look for small cracks or inverter issues.
• Keep nearby branches trimmed to cut shade and stop leaves collecting.

Some installers require a service within a set period to keep their warranty valid, so check your paperwork. With regular upkeep, the Energy Saving Trust says panels should work well for their full lifespan.

Keeping an eye on generation

• Every MCS solar installation includes a way to record total generation, readable without tools or ladders.
• Glance at your app or generation meter now and then. Lower figures on cloudy days and in winter are normal; a sudden drop in bright sunlight can mean a fault, often with the inverter.
• Compare each year's generation with the estimate in your quote, allowing for the weather: 2024 was an unusually dull year for solar and 2025 an unusually sunny one.

If your roof needs work during the panels' life, they'll need taking off and refitting. If your roof is near the end of its life, it's usually cheaper to sort it before the panels go on.

Can you recycle solar panels?

Yes. Solar panels are covered by the WEEE regulations for electrical waste, in their own category, and count as household waste wherever they're installed, so producers fund their collection and recycling. When panels reach the end of their life, or if you're replacing old ones, ask your installer how they'll be collected.

Most of a panel is straightforward to recycle. Glass makes up the largest share of its weight, and the aluminium frame is easily separated and fully recyclable, according to the Royal Academy of Engineering's Ingenia magazine. The silicon cells, and the small amounts of silver and copper in them, are harder to recover.

How solar panels are recycled

• The aluminium frame and junction box are removed.
• The layers are separated, for example with heat, so the glass comes away from the silicon cells.
• The rest is sorted into glass, plastics, silicon and metals such as silver and copper, which can then be purified.

Not every recycler does the later steps. Recovering the silicon and silver takes specialist processes, which plants in Germany and France are developing. So the glass and aluminium are reliably recycled, but how much of the rest is recovered depends on where the panels go.