Solar Panel Degradation Calculator
See how your solar panel output declines over time and find exactly when panels hit the 80% warranty threshold.
Panel Details
Why Solar Panels Degrade
Solar panels lose output over time primarily due to UV-induced degradation of the encapsulant and anti-reflective coating, thermal cycling stress on cell connections, and light-induced degradation (LID) in silicon cells. The industry standard degradation rate is 0.5% per year, though premium panels can achieve 0.3%/year and budget panels may degrade at 0.7–1%/year.
The 80% warranty threshold is the benchmark most manufacturers use for their power output warranty. A panel rated at 400W at the 80% threshold would still produce 320W. Most quality panels carry a 25–30 year performance warranty guaranteeing output above 80% of nameplate capacity. If your panels fall below this threshold before the warranty expires, you may be entitled to replacement.
For system sizing and financial modeling, use the 0.5%/year degradation rate as a conservative estimate. Actual degradation depends on climate (high-temperature environments degrade faster), panel technology (monocrystalline PERC is more stable than older polycrystalline), and installation quality.