How Long Do Solar Panels Last? Lifespan, Degradation, and What to Expect

Solar panels are one of the most durable consumer products ever manufactured. A well-made silicon panel has no moving parts, no fuel to burn, and no mechanical wear — which is why panels installed in the 1980s and 1990s are still generating electricity today, often at 80% or more of their original rated output. The real answer to "how long do solar panels last" is: longer than almost any other home improvement you can make.

The industry standard warranty is 25 years of production performance, typically guaranteeing output no lower than 80–82% of original rated wattage at year 25. A 400W panel warranted to 80% still produces 320W after a quarter-century of continuous outdoor exposure. This is the "floor" manufacturers commit to — real-world panels frequently outperform it.

The degradation rate is the key number. According to a 2023 NREL meta-analysis of over 11,000 solar installations, the median degradation rate for crystalline silicon panels is 0.5% per year. That means a panel loses about half a percent of its output each year. A 400W panel degrades to 380W by year 10, 360W by year 20, and 340W by year 30. This is why our solar savings calculator applies 0.5%/year degradation by default.

Premium manufacturers like SunPower and REC claim degradation rates as low as 0.25–0.3% per year on their top-tier panels. Budget panels from less-established manufacturers often degrade at 0.7–1.0% per year. The panel quality you choose at installation locks in your long-term output trajectory — which is why the cheapest panel is not always the best value over a 25-year horizon.

What actually kills solar panels? The two leading causes of premature failure are delamination (moisture entering the encapsulant) and potential-induced degradation (PID), an electrical phenomenon that can shunt current away from cells. Both are largely design-quality issues. Third-party certification (IEC 61215 and 61730) tests panels against simulated decades of weathering — look for these certifications on any panel you consider.

Inverters have shorter lifespans than panels. String inverters typically last 10–15 years and cost $1,000–$2,500 to replace. Microinverters (Enphase IQ8 series) carry 25-year warranties and in practice have shown very low failure rates. Budget for at least one inverter replacement over a 25-year ownership period if you have a string inverter — our solar savings calculator includes this cost in the long-term projection.

The practical implication: if your panels come with a 25-year production warranty and degrade at 0.5%/year, you are looking at 30–35 years of economically meaningful output from a quality installation. The system does not die at year 25 — the warranty simply expires. Many homeowners choose to add capacity at that point rather than replace the original panels.