Solar Panel Degradation Calculator

Enter your system's starting output and annual degradation rate to see production at any future year.

ā± ~10 secšŸ“‰ 25-year outlookšŸ”’ No signup

Result

9,680 kWh
Production in target year
% of original output88%
Lifetime total (25 yrs)262,000 kWh

Most tier-1 panels degrade 0.3-0.6% per year and are warrantied for roughly 85-88% output at year 25 — check your panel's actual warranty for exact figures.

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Why panels lose output over time

Year N output = Year 1 output Ɨ (1 āˆ’ degradation rate)^(Nāˆ’1)

Solar cells degrade gradually from UV exposure, thermal cycling, and micro-cracking — a slow, predictable decline rather than a cliff. This projects your system's output at any future year so you can sanity-check a payback or ROI calculation against realistic long-term production instead of assuming year-1 output forever.

Degradation is a slow, predictable curve rather than a cliff — a panel doesn't work fine for 24 years and then suddenly fail in year 25. Understanding the shape of that curve matters most when comparing a 25-year production estimate across panels with different published degradation rates, since even a small annual difference compounds meaningfully over two and a half decades.

Frequently asked questions

Does a higher-quality panel degrade slower?

Generally yes — premium panels with better cell technology and encapsulation often carry degradation warranties near 0.3-0.4%/year, versus 0.5-0.7% for budget panels.

Should I use this lower output for payback calculations?

For most systems the difference is small enough to ignore in early years, but for a 20-25 year total production estimate, factoring in degradation gives a more honest number than assuming flat output.

Is degradation rate the same for every panel from the same manufacturer?

Generally consistent within a product line, since degradation rate is largely a function of cell technology and encapsulation quality — but different product lines from the same manufacturer (budget vs premium) can carry different published rates.

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