Solar panels last 25 to 30 years at a minimum, and most keep generating well beyond that. What changes is output: panels lose about 0.5% of their power each year on the median of long-term studies, so after 25 years a panel still makes roughly 88% of what it did when new. The inverter is the part that wears out first, typically after 10 to 15 years.
- 25 to 30 years typical manufacturer performance warranty on panels
- 0.5% a year median output loss across long-term field studies reviewed by the US National Renewable Energy Laboratory
- 88.85% minimum output guaranteed after 30 years on a current premium panel (LONGi Hi-MO X10)
- 10 to 15 years typical life of a string or hybrid inverter, around £800 to replace
That long life is what makes solar pay: most systems pay for themselves in their first decade and spend the next two or more producing electricity for almost nothing. Below we set out how long each part lasts, how much output a system loses, and what you can do to make sure yours goes the distance.
How long each part of a solar system lasts
A solar system is several components with different working lives. The panels are the longest-lived part by a wide margin.
| Component | Typical working life | Typical manufacturer warranty | What happens at end of life |
|---|---|---|---|
| Solar panels | 30 years or more | 25 to 30 years (performance) | Keep generating at reduced output |
| String or hybrid inverter | 10 to 15 years | 10 to 12 years | Replaced, usually once in the system's life |
| Microinverters | Around 25 years | 20 to 25 years | Replaced individually if one fails |
| Home battery | 10 years or more | 10 years or more | Capacity fades gradually |
| Mounting rails and roof hooks | Life of the system | Covered by workmanship warranty | Reused if panels are swapped |
| Cabling, isolators, connectors | Life of the system with checks | Covered by workmanship warranty | Isolated parts replaced if damaged |
On our installations you also get a 10-year workmanship warranty backed by insurance, which covers the fitting itself: the roof fixings, cabling and connections. You can read what is covered on our solar warranties page.
How much output do panels lose each year?
All panels lose a little power each year as the materials age. There are two useful reference points.
- Field studies. A review of nearly 2,000 degradation rates measured over 40 years of field testing, by Dirk Jordan and Sarah Kurtz of NREL, found a median loss of 0.5% a year. A later update covering more than 11,000 data points found the same figure for crystalline silicon panels using only high-quality data.
- Manufacturer guarantees. Premium modern panels promise less. The LONGi Hi-MO X10, for example, guarantees no more than 1% loss in the first year and 0.35% a year after that, leaving at least 88.85% of rated output after 30 years.
Heat is one of the main things that speeds up ageing, and the NREL review found higher loss rates in hot desert climates. England's mild temperatures are kind to panels by comparison.
Worked example: 30 years of a 4.4kW system in Birmingham
Our PVGIS modelling for a south-facing roof at 35 degrees in Birmingham gives 972 kWh per kWp a year. For a 4.4kW system: 972 x 4.4 = 4,277 kWh in year one. Applying the 0.5% median loss each year after that:
| Year | Output at 0.5% a year loss | Share of original output | LONGi warranted minimum |
|---|---|---|---|
| 1 | 4,277 kWh | 100% | 99.0% |
| 10 | 4,088 kWh | 95.6% | 95.9% |
| 20 | 3,888 kWh | 90.9% | 92.4% |
| 25 | 3,792 kWh | 88.7% | 90.6% |
| 30 | 3,698 kWh | 86.5% | 88.9% |
How the sum works: year 10 output is 4,277 x 0.995 to the power of 9 = 4,088 kWh. Add every year up and the system makes about 100,700 kWh over 25 years and about 119,400 kWh over 30. At the October to December 2026 price cap rate of 26.32p per kWh, every 1,000 kWh you use yourself is worth £263.20, and the output in years 26 to 30 alone comes to about 18,700 kWh. Even if every one of those units were exported at 12p, that is over £2,200.
The takeaway: the loss is slow enough that a 20 year old system is still doing about 90% of its original job. See how that feeds into returns in our guide to the solar panel payback period.
Performance vs product warranty: panel makers usually give two warranties. The product warranty covers defects in the panel itself. The performance warranty guarantees a minimum output over 25 or 30 years. Check the length of both, as the product warranty is sometimes shorter.
The inverter: the part you will replace
The inverter converts the direct current from your panels into the alternating current your home uses, and it works hard every day of the year. Its electronics, fans and capacitors wear out long before the panels do. A string or hybrid inverter typically lasts 10 to 15 years, and its manufacturer warranty is usually 10 to 12 years.
Plan for one replacement in the life of the system. The Energy Saving Trust puts the cost at around £800 for a standard inverter; hybrid inverters that also run a battery can cost more. The good news is that the replacement is usually a better, more efficient model than the original.
If you already have panels and your inverter is nearing replacement, that is often the best moment to add storage with a hybrid inverter. Our battery retrofit service covers this.
What shortens a solar panel's life
- Poor installation. Loose connectors, badly sealed roof fixings or cables rubbing on tiles cause most long-term faults. This is why the installer matters as much as the panel brand, and why MCS certification and a workmanship warranty are worth insisting on.
- Walking on panels. Standing on a panel can create microcracks in the cells that are invisible but cut output over time.
- Harsh cleaning. Pressure washers, abrasive brushes and strong detergents can damage the glass coating and seals. Our solar panel maintenance guide explains what is safe.
- Hot spots from shading or debris. A leaf mat or bird mess sitting on one part of a panel for months can make those cells run hot. Modern panels have bypass diodes to limit this, but persistent partial shading is still best avoided.
- Nesting birds. Pigeons nesting under panels can damage cables. Bird mesh fitted around the array edge prevents it.
Signs your system is ageing badly
A healthy system loses output slowly and evenly. Watch your monitoring app and compare each month with the same month last year. Be concerned if you see:
- A drop of more than a few percent year on year that the weather does not explain.
- One panel or string producing much less than the others, on systems with panel-level monitoring.
- Inverter error codes, or the inverter restarting repeatedly.
- Visible damage: cracked glass, brown discolouration, or bubbles in the backing sheet.
Older systems: what 15 year old panels tell us
The Feed-in Tariff scheme, introduced on 1 April 2010, put solar on a great many English roofs in its early years. Many of those systems are now 15 years old and still running on their original panels, often on their second inverter. If you are buying a house with an older system, ask for the MCS certificate, the inverter age and a year or two of generation readings. Our guide to solar panels and selling your house covers what buyers ask.
At the end of their life
Solar panels are covered by the UK's WEEE Regulations 2013 for electrical waste. They must not go to landfill or a general skip, and producers who put panels on the UK market must finance their collection and recycling. A panel is mostly glass in an aluminium frame, and both materials can be recovered.
In practice, many owners replace panels before they wear out, simply because newer panels are more powerful. Panels from the early 2010s were rated well below the 440W panels in our standard solar panel installations, which produce far more from the same roof space.
Honest caveats
- Degradation rates are averages. A small share of panels fail early from manufacturing defects, which is what the product warranty is for.
- A warranty is only as good as the company behind it. Well-established panel makers and an insurance-backed workmanship warranty reduce that risk.
- Battery lifespans depend heavily on how hard the battery is cycled. A battery charged and emptied twice a day ages faster than one used once.
Sources
Degradation rates: Jordan and Kurtz, Photovoltaic Degradation Rates, an Analytical Review, NREL. Panel warranty: LONGi Hi-MO X10 product page and datasheet. Inverter replacement cost: Energy Saving Trust, solar power facts. Battery warranty: Tesla Powerwall 3 datasheet. Feed-in Tariff start date: Ofgem, Feed-in Tariffs. Electrical waste rules: WEEE Regulations 2013, Schedule 1 and gov.uk, EEE producer responsibility. Unit rate: Ofgem energy price cap, October to December 2026. Export rate: Outgoing Octopus. Generation: our modelling with PVGIS, European Commission Joint Research Centre.
