How long do solar panels last in the UK?

How long do solar panels actually last?

Most solar panels sold in the UK carry a 25-year performance warranty, guaranteeing the panel will still produce at least 80% of its rated output after 25 years. In practice, many systems continue generating electricity well beyond that, with installations from the 1990s still in operation.

The 25-year figure is a floor, not a ceiling. It reflects what manufacturers are confident enough to guarantee in writing.

What is solar panel degradation?

Solar panels lose a small percentage of their efficiency each year, a process known as degradation. Industry-standard figures put annual degradation at 0.5% to 0.8% per year for modern crystalline silicon panels, which is the technology used in the vast majority of UK residential installations.

After 25 years at 0.7% annual degradation, a panel produces approximately 84% of its original rated output. This sits comfortably within the performance warranty threshold most manufacturers set at 80%.

How long does a solar inverter last?

The inverter is typically the first major component that needs replacing. Most string inverters carry a 5 to 10-year warranty and have an expected lifespan of 10 to 15 years. Budget for inverter replacement when planning the long-term cost of ownership of a solar system.

Microinverters and power optimisers often carry longer warranties, some up to 25 years, and may outlast a standard string inverter in the same installation.

What affects how long solar panels last?

Several factors influence how well a solar system holds up over time:

• Installation quality — Panels installed incorrectly or with substandard mounting can suffer physical damage and accelerated degradation. MCS-certified installations follow a verified standard that reduces this risk.
• Cleaning and maintenance — Dirty panels produce less electricity. An annual inspection and clean keeps output close to the rated figure.
• Manufacturer quality — Panels from established manufacturers with verifiable track records carry less risk of early failure than cheaper, unverified alternatives.
• Roof condition — Panels installed on a roof that later needs work require removal and reinstallation, which adds cost and risk. Assess the roof before installing.

Does the UK climate shorten solar panel lifespan?

No. Solar panels are rated to operate in temperatures from -40°C to +85°C, well outside anything the UK experiences. Wind, rain, and frost do not materially affect well-mounted panels with intact seals and frames.

High temperatures can reduce panel efficiency slightly in the short term. The UK's moderate climate is, in some respects, better for sustained output than very hot countries, even though those countries receive more annual sunlight hours.

What warranty should you expect from an MCS-certified installation?

A typical solar panel comes with two separate warranties: a product warranty, usually 10 to 15 years, covering manufacturing defects; and a performance warranty, usually 25 years, guaranteeing a minimum output level. Both are worth reading carefully.

MCS certification requires that installers meet MCS installation standards, which include workmanship obligations that sit alongside the manufacturer warranties. This matters if you ever need to make a claim.