How many years solar panels last?

Solar panels typically last 25 to 30 years — a 4 kW system can save £10,400 in GB electricity bills over that lifespan

If you are researching solar panels, the most direct question is often simply: how many years solar panels last before they need replacing. The standard answer, based on manufacturer warranties and field data, is 25 to 30 years for a functional system. A typical 4 kW system installed in 2026 saves roughly £520 per year on average for a south-facing, unshaded home in Great Britain (Energy Saving Trust, 2026). Over 20 years that totals £10,400, and over 30 years it reaches £15,600.

These savings assume you use roughly half the generated electricity on-site and export the rest at the Smart Export Guarantee (SEG) rate. Actual savings vary with your household consumption and electricity tariff, but the 25–30 year lifespan is the baseline for financial planning.

The standard manufacturer warranty guarantees 25 years at 80% output

Most Tier-1 panel manufacturers — including LG, SunPower, REC, and Longi — offer a 25-year linear performance warranty. This guarantees that after 25 years, the panel will still produce at least 80% of its original rated output. The product warranty (against manufacturing defects) is typically shorter, at 10–12 years, but the performance warranty is the key figure for longevity (MCS product database, 2026).

After the warranty period ends, panels do not stop working. They continue to generate electricity, but at a gradually reduced capacity. The usable life often extends to 30 years or more, with output dropping to 70–80% of the original rating. This makes the 25-year warranty a conservative baseline rather than a hard expiry date.

Quick numbers — warranty, degradation, and lifespan for a typical 4 kW system

Degradation rates for modern monocrystalline panels average around 0.5% per year, according to the National Renewable Energy Laboratory (NREL photovoltaic degradation review, 2026). This means a panel loses roughly 12.5% of its original capacity after 25 years and about 15% after 30 years.

Solar panels do not stop working after the warranty — they just produce less

Panels degrade gradually and predictably. At a 0.5% annual degradation rate, a 4 kW system producing 3,400 kWh in year one will generate about 2,975 kWh in year 25 and roughly 2,890 kWh in year 30. The system is still functional but less efficient (NREL degradation review, 2026).

The inverter, however, has a shorter life. String inverters typically last 10–15 years, and microinverters last 20–25 years. You should budget for at least one inverter replacement during the panel’s life, costing £800–£1,200 for a 4 kW system (Energy Saving Trust, 2026). Replacing the inverter at year 15 can extend the system’s overall life to 30 years without needing new panels.

How many years solar panels last depends on the type and quality

Monocrystalline panels, the most common type in 2026, have the longest lifespan at 25–30 years, with premium models degrading as slowly as 0.3% per year. Polycrystalline panels, now increasingly rare, last 20–25 years and degrade at around 0.7% per year. Thin-film panels (CdTe or CIGS) last 20–25 years but degrade faster, at 0.8–1% per year (MCS product database, 2026).

Panel quality also matters. Tier-1 manufacturers typically use higher-grade silicon and better encapsulation, resulting in lower degradation rates. Cheaper panels from lesser-known brands may degrade at 0.7–1% per year, reducing their effective lifespan to 20–25 years. Always check the MCS certification and the linear performance warranty before purchasing.

How to verify your installer and panels are certified for the long haul

To qualify for the Smart Export Guarantee (SEG) in Great Britain, both the panels and the installer must be certified under the Microgeneration Certification Scheme (MCS). You can check the register at mcscertified.com to confirm a product’s warranty terms and certification status. Installers should also be TrustMark-registered for consumer protection (GOV.UK, 2026).

For the inverter, ask the installer for a G99 or G100 Grid Code compliance certificate. This ensures the inverter meets UK grid connection standards. Without it, your system may not be eligible for SEG payments or could face connection delays.

How many years solar panels last

Solar panels last 25 to 30 years as a working system, with most manufacturers guaranteeing 80% output at year 25. After 30 years, panels still produce electricity but at roughly 70–75% of original capacity — they are not “dead,” just less efficient. The 25-year figure is the industry standard for the performance warranty; the physical lifespan can extend to 35+ years with good maintenance (Energy Saving Trust, 2026).

If you maintain the panels by cleaning them occasionally and replacing the inverter when needed, the system can continue generating useful power well beyond the warranty period. The key metric is not the calendar date but the output level — once it drops below 70% of the original rating, replacement becomes economically sensible.

Planning for replacement — what to budget and when

Most homeowners replace panels after 25–30 years when output drops below 70% or when the inverter fails and the cost of repair outweighs the savings. A full replacement (panels plus inverter) for a 4 kW system in 2026 costs £6,000–£8,000, depending on panel type and installation complexity (Energy Saving Trust, 2026).

If the inverter fails at year 15, replacing just the inverter for £800–£1,200 can extend the system life to 30 years without replacing panels. This is often the most cost-effective strategy. Compare solar panel replacement costs with new installation costs to decide whether to repair or replace. Read our guide to solar panel maintenance to extend panel life beyond 30 years.