Most solar panels carry a 25-year performance warranty, not a lifespan limit
The figure most homeowners search for is 25 years. This is the duration of the industry-standard performance warranty, not a hard expiry date for the panels themselves. The Microgeneration Certification Scheme (MCS) 012 standard requires manufacturers to guarantee that panels will produce at least 80% of their original rated output after 25 years (MCS, 2026).
Solar panels last 25 years under a performance warranty but can work for 30 to 40 years. Degradation is 0.5% to 0.8% per year, so output after 25 years is still 80% or more.
- Industry standard warranty guarantees 80% output after 25 years.
- Solar panels can physically last 30 to 40 years.
- Inverters need replacement every 10 to 15 years.
- Panels degrade at 0.5% to 0.8% per year on average.
- Systems installed before 2010 are still operating in the UK.
- Most solar panels carry a 25-year performance warranty, not a lifespan limit
- Quick numbers — solar panel degradation rates and expected output over time
- The difference between performance warranty, product warranty, and actual lifespan
- How to check if your solar panels are still working after 10 or 20 years
- Eligibility for the Smart Export Guarantee (SEG) — how panel age affects payments
- Who qualifies for grants and who does not — the age of your panels matters
- How to verify an installer and ensure your panels will last the full 25 years
Panels often continue generating electricity beyond this point, but at a gradually declining rate. The physical lifespan of the silicon cells can reach 30 to 40 years. However, the inverter, which converts DC electricity to AC for home use, typically needs replacing around year 10 to 15 (Energy Saving Trust, 2026). The 25-year figure is a warranty guarantee, not a switch-off date.
A Department for Energy Security and Net Zero (DESNZ) evidence review confirms that most residential solar PV systems installed in the UK in the 2000s are still operating (DESNZ, 2026). Homeowners should plan for inverter replacement as a routine cost, not a sign of system failure.
Quick numbers — solar panel degradation rates and expected output over time
Solar panels lose efficiency each year. This is called degradation. The National Renewable Energy Laboratory (NREL) found that modern panels degrade at an average rate of 0.5% to 0.8% per year (NREL, 2026). The table below shows typical output over time for a 4kW system generating 3,500 kWh in year one.
| Year of operation | Expected output vs. new | Typical degradation rate |
|---|---|---|
| Year 1 | 100% | 0.5–0.8% |
| Year 10 | 93–95% | 0.5–0.8% per year |
| Year 20 | 86–90% | 0.5–0.8% per year |
| Year 25 | 80–87% | 0.5–0.8% per year |
| Year 30 | 76–85% | 0.5–0.8% per year |
DESNZ domestic solar performance data for the UK shows that systems installed before 2010 are still producing at an average of 85% of their original output (DESNZ, 2026). Degradation is gradual, not sudden.
The difference between performance warranty, product warranty, and actual lifespan
The 25-year performance warranty covers output. It guarantees that panels will still produce at least 80% of their original power after 25 years. The product warranty, typically 10 to 12 years, covers defects in materials and workmanship, such as cracked glass or junction box failure (MCS installer standards, 2026). These are two separate protections.
Actual lifespan depends on panel quality, local climate, and maintenance. Panels exposed to heavy coastal salt spray or frequent hail may degrade faster than those in inland suburban conditions. Homeowners should check both warranty types before purchase. A 25-year performance warranty with a 10-year product warranty is common. A 25-year product warranty is rarer and indicates higher quality.
The actual lifespan of the silicon cells can reach 30 to 40 years, but the system’s useful life is often determined by inverter reliability and the availability of replacement parts. How to extend the life of your solar panel system
How to check if your solar panels are still working after 10 or 20 years
Monitor daily kWh output through the inverter display or a connected app. Compare current generation to the system’s original estimated annual output, which should be on the installer’s commissioning sheet. An annual degradation of 0.5% to 0.8% is normal (DESNZ Solar PV performance report, 2026).
A sudden drop of 20% or more in one year indicates a fault. Common causes include a failed inverter, a blown string fuse, or shading from new tree growth. These are not normal aging. Contact an MCS-certified installer to diagnose the issue.
Use the MCS database at mcscertified.com to check if the original installer is still registered. If they are not, a new MCS-certified installer can still carry out repairs and issue warranty claims on compatible panels.
Eligibility for the Smart Export Guarantee (SEG) — how panel age affects payments
SEG payments are based on the electricity you export to the grid, not the age of your panels. Older panels that still generate and export can qualify, provided they meet the scheme’s requirements. Panels installed under the old Feed-in Tariff (FiT) still receive FiT payments for 20 years. After that period ends, the household can switch to a SEG tariff (Ofgem SEG guidance, 2026).
Panels older than 25 years may not be eligible for a new SEG contract if they do not meet current MCS standards. The installer who fits the panels must be MCS-certified for the system to qualify for SEG. If the original installation was not MCS-certified, you cannot join SEG. Homeowners should confirm their installer’s MCS registration before any new installation or repair.
FiT payments are index-linked and fixed at the original tariff rate for 20 years. After that, the household can export under SEG at the prevailing market rate, which is typically lower. Smart Export Guarantee rates 2026
Who qualifies for grants and who does not — the age of your panels matters
The ECO4 scheme and the Great British Insulation Scheme do not cover solar panel replacement or repair for existing systems. These schemes only fund new installations for eligible low-income households (GOV.UK ECO4 guidance, 2026). If your panels are older than 25 years and failing, you cannot get a grant to replace them under current rules.
Low-income households with panels older than 20 years may qualify for a free energy audit under ECO4, but the audit will not pay for panel replacement. The audit may recommend other measures such as insulation or a heat pump. Panels older than 25 years may need replacement to qualify for any future grant schemes, but no such scheme currently exists.
Homeowners with panels under 10 years old are unlikely to qualify for any grant. They are expected to use the product warranty or home insurance for repairs. If the panels are still under the performance warranty, the manufacturer may replace them if output drops below 80% of the original rating.
How to verify an installer and ensure your panels will last the full 25 years
Only use MCS-certified installers. Check the MCS register at mcscertified.com before signing a contract. For government-backed schemes, the installer must also be TrustMark registered (GOV.UK TrustMark guidance, 2026). Gas Safe Register is irrelevant for solar panels. Electrical work must be covered by NICEIC or NAPIT registration, which the installer should provide.
Ask for the specific panel model’s datasheet. It must state the 25-year performance warranty and the degradation rate. Reputable manufacturers such as Longi, Trina, and Jinko publish these figures. Avoid any installer who cannot provide a datasheet or who offers a “lifetime warranty” without defining the term in years.
Ensure the installer provides a full commissioning report, including expected annual kWh output. This document is your baseline for monitoring performance over the next 25 years. Keep all paperwork, including the MCS certificate, in a safe place. Without it, you cannot prove eligibility for SEG or future grants.
Frequently Asked Questions
Solar panels last 25 years under a performance warranty but can physically operate for 30 to 40 years. The Energy Saving Trust confirms inverters need replacing around year 10 to 15.
No, solar panels do not stop working after 25 years. The 25-year figure is a warranty guarantee, not a switch-off date, according to the MCS 012 standard.
Modern solar panels degrade at an average rate of 0.5% to 0.8% per year, according to the National Renewable Energy Laboratory (NREL). After 25 years, output is typically 80% to 87% of original.
You should replace your solar inverter every 10 to 15 years. The Energy Saving Trust advises planning for this as a routine cost, not a sign of system failure.
Yes, solar panels work in the UK after 20 years. A DESNZ evidence review confirms most residential systems installed in the 2000s are still operating.
