How long do solar panels last?
Solar panels don't switch off on a set date. What's written down is the output the manufacturer guarantees after 25 or 30 years, and that's the number to compare.
Solar panels don't stop working on a fixed date. They lose output slowly. The four manufacturer datasheets we checked all carry a power warranty of 25 or 30 years, and on each one the manufacturer guarantees that the panel will still deliver at least 87.4% to 88.9% of its rated power at the end of that period. When the warranty ends, the panels keep producing; what changes is that nobody guarantees how much.
To judge a panel properly, keep three things apart: how long it stays useful, how long the warranty covers defects, and the minimum output the manufacturer guarantees over time. The rest of this guide explains each one, with real figures, and what to do if your output drops.
Three different "lifespans"
"25 years" or "30 years" means little until you know what it covers.
My yearly electricity use is
Your yearly electricity use helps us size your solar panel system.
| What's quoted | What it tells you | What it doesn't prove |
|---|---|---|
| Working life | How long the panel stays useful on your roof | That it produces the same every year |
| Product warranty | The manufacturer will deal with specified defects in materials and workmanship for a set period | That removal, delivery and refitting are paid for |
| Power (performance) warranty | A minimum output the panel must still reach, following a set curve and conditions | A fixed number of kWh for your whole system |
| Workmanship warranty | The installer's responsibility for the installation work | The manufacturer's performance claims |
A panel's power, in watts, is measured under standard test conditions. Your system's annual output, in kWh, depends on weather, shade, temperature, orientation, losses and whether everything is running. Our guide to how solar panels work explains the difference. So one poor week of kWh doesn't mean the cells are wearing out.
When a warranty ends, the panel doesn't stop working. And a long warranty isn't enough on its own: check the guaranteed output level, the exclusions, how a fault has to be measured, which company is responsible, and what costs would still fall on you.
What four real datasheets say
| Panel (datasheet edition) | Product warranty | Power warranty | Max. loss in year 1 | Max. loss per year after | Guaranteed at the end |
|---|---|---|---|---|---|
| Trina Solar Vertex S+ NEG9R.28 (EU, 2026_A) | up to 25 years | 30 years | 1% | 0.4% (years 2–30) | 87.4% at year 30 |
| JinkoSolar Tiger Neo 54HL4R-B (F1.3-EN) | 25 years | 30 years, linear | 1% (99% after year 1) | 0.40% | 87.4% at year 30 |
| LONGi Hi-MO X6 Scientist LR5-54HTH (V19 EN) | 25 years, materials and processing | 25 years, linear | under 1.5% | 0.40% (years 2–25) | 88.9% at year 25 |
| AIKO Neostar 2P AIKO-A-MAH54Mw (V4.1, Oct 2025) | 15 years, extendable to 25 | 30 years, linear | 1% or less | 0.35% or less (years 2–30) | 88.85% at year 30 |
These figures apply to the models and datasheet editions shown. What counts for a claim is the warranty document that applies to the product sold in the UK: ask for it alongside the datasheet, and check the conditions, exclusions and who handles claims here. Our guide to the best solar panels compares brands on these points.
Compare the guaranteed output, not the yearly percentage
The table shows the trap. AIKO has the lowest yearly loss (0.35% or less), but its product warranty starts at 15 years, not 25. LONGi has the same yearly loss as Jinko (0.40%) but a shorter period, 25 years against 30, so its end figure is higher (88.9% against 87.4%) simply because the finish line is closer.
Two practical rules:
- Compare the guaranteed output at the end, and say at which year. "88.9% at 25 years" and "87.4% at 30 years" are different promises; neither is simply better at a glance.
- Look at the two warranty periods separately. Product and power warranties can run for different lengths on the same panel, as with AIKO, and they cover different things: a panel that breaks isn't the same as a panel that produces less.
How to read a curve. For the Trina panel, the minimum at year 30 is 100% − 1% − (29 × 0.4%) = 87.4%. For its 475 W version, that's 475 W × 0.874 = 415 W under the warranty's test conditions. It doesn't mean the panel will produce exactly 415 W at midday in 30 years' time. Redo this with your own panel's document: model, rated power, first-year loss, yearly loss, period and end figure.
What that means in kWh
Illustration. A 4 kWp south-facing system in London produces about 4,075 kWh in a typical year, according to PVGIS (4 × 1,018.84 kWh per kWp; version 5.3, 35° tilt, 14% system losses). If the panels were exactly at an 87.4% warranty floor in year 30, and nothing else changed, the same roof would produce about 3,562 kWh a year (4,075 × 0.874).
That's our arithmetic on a warranty floor, not a forecast: a warranty sets the minimum, not the path your panels will actually follow, and weather, shading and the rest of the system change year to year. It shows why ageing alone rarely changes the decision to buy. Cost per kWp, and how much of your electricity you use at home, matter far more.
How panels age, and what else lowers output
Panels spend decades outdoors through temperature swings, damp, UV light, wind and snow load. A slow loss of power is built into the warranty curves. Broken glass, visible delamination, water ingress or a sudden drop in output are different problems and need checking.
Your system's output can also fall while the panels are fine:
- a new shadow from a tree or extension;
- a communication fault hiding data in the app;
- an inverter or microinverter that has stopped;
- a tripped isolator or protection device;
- bird droppings, nests or debris covering part of the array;
- two periods being compared in different weather.
The inverter has its own life span and warranty, separate from the panels, and replacing it doesn't mean the panels need replacing. Our guide to microinverters vs string inverters explains which component does what.
Watch the right signals
Useful monitoring compares against a baseline, not a feeling. Keep your installer's performance estimate, the system size, the panel layout, serial numbers and yearly output. Then compare equivalent months or years, allowing for weather and changes around the roof. Our maintenance guide sets out a simple routine.
| What you see | First check | Sensible next step |
|---|---|---|
| No data, but the inverter display looks normal | Wi-Fi, data logger and when the last reading arrived | Check the manual; don't open the inverter |
| No output in full daylight | The inverter's display and alerts, a possible power cut, whether the whole system is off | Note the code and contact your installer or the manufacturer |
| Slow decline over several comparable periods | History, new shade, building work or changed settings | Have the data analysed before blaming the panels |
| One roof face or string lags behind | Per-string or per-panel data if you have it | Ask for a documented professional diagnosis |
| Broken glass, hanging cable or scorch marks | Look from a safe place | Keep people away and call a professional; touch nothing |
Don't go on the roof to confirm a fault, and don't open any electrical equipment.
Check your warranties and your rights
Before you buy, ask for four separate documents: the datasheet for the exact panel offered, the product warranty, the power warranty and the installer's workmanship warranty. For each one, note:
- the company legally responsible, and how to contact it in the UK;
- the start date and whether the warranty has to be registered;
- the models and serial numbers covered;
- exclusions for installation, environment, cleaning or monitoring;
- the evidence and measurement method needed for a claim;
- the remedy: repair, replacement, refund or something else;
- whether access (such as scaffolding), removal, delivery and refitting are covered. In a replacement, these costs add up quickly.
A manufacturer's warranty sits on top of your legal rights, not instead of them. Under the Consumer Rights Act 2015, goods must be of satisfactory quality, which includes durability, and a service such as an installation must be carried out with reasonable care and skill. Those rights are against the business that sold or installed the system. If a fault appears within six months of delivery, it's presumed to have been there from the start unless the business shows otherwise. If your installer belongs to the RECC consumer code, it must also give at least a two-year workmanship warranty that is insurance-backed and transferable. Since MCS no longer requires consumer-code membership, check whether yours is a member.
A 30-year promise is only worth as much as the company behind it being around, and reachable in the UK, in 30 years. Keep the quote, contract, invoice, datasheet, warranty documents, MCS certificate, commissioning date and your monitoring history together. Our guide to choosing a solar installer covers what to ask before you sign.
Keep, repair or replace?
An older panel doesn't need replacing just because newer ones are more efficient. If it's safe, undamaged and the system still performs as expected, keeping it is usually the simplest choice. Newer panels' higher efficiency matters most when roof space limits your system or a replacement is already justified.
Ask for a diagnosis when a drop persists without explanation, an alert keeps returning, one group of panels behaves differently or damage is visible. A good engineer separates a panel fault from a connection problem, the inverter, protection devices, shade and the measurement itself. Get the readings and conclusion in writing before agreeing to a full replacement.
Swapping a few panels for more powerful ones isn't a like-for-like change. Voltage, current, connectors, mechanical load, fixings, string design and the inverter's limits all have to stay compatible. Have the whole system checked before anything is changed.
At the end of their life
Solar panels count as electrical waste in the UK. They're covered by the Waste Electrical and Electronic Equipment (WEEE) Regulations 2013, in the category "consumer equipment and photovoltaic panels", which requires producers to finance their collection, treatment, recovery and recycling through compliance schemes. That doesn't mean taking them off your roof is free. Don't put panels in general waste. If yours are being removed, ask the installer how they'll be taken for recycling and for a record, and include access and disposal in the quote.
Frequently asked questions
How long do solar panels last in the UK?
There's no fixed end date. On the four manufacturer datasheets we checked, power warranties run for 25 or 30 years and guarantee 87.4% to 88.9% of rated output at the end. Panels keep working after that, producing slowly less, unless damage or an installation fault ends their life sooner.
How much efficiency do solar panels lose each year?
On the four datasheets we checked, the maximum loss is 1% to 1.5% in the first year, then 0.35% to 0.40% a year after that. These are guaranteed maximums, not measured losses.
Do I need to replace all my panels after 25 years?
No. Twenty-five years can be a warranty period or an average assumption, depending on the document. Decide based on condition, safety, measured output, compatibility and the cost of the work. An age alone doesn't diagnose a system.
Does a 30-year warranty guarantee my yearly kWh?
No. It guarantees a percentage of each panel's rated power, measured under set conditions. Your system's kWh also depend on weather, orientation, shade, the other components and any downtime.
Does the warranty pay for labour and scaffolding?
Check the warranty document. Often the panel is covered but access, removal, delivery and refitting may not be. Ask for this in writing before you sign, because in a replacement these costs add up quickly.
Can solar panels be recycled?
Yes. In the UK they're treated as electrical waste under the WEEE Regulations, which make producers pay for their collection, treatment and recycling or recovery. Removal from the roof is a separate cost, so ask your installer how old panels will be recycled.