Solar Panel Degradation Calculator
Forecast year-by-year output decline at 0.4–0.6%/yr and check production against the linear power warranty.
Panels fade slowly — median 0.5%/yr per NREL's degradation studies — but over 25 years that compounds to ~12% lost capacity. Forecast your plant's year-by-year output, total lifetime energy, and whether measured production has fallen below the manufacturer's linear warranty line (a claimable event).
Output(y) = Year-1 × (1 − 0.5%)^y. Compare the year-25 row against your panel's linear power warranty — a plant below the warranty line has a claim.
Engineering estimate from published standards and typical equipment data. Site conditions, equipment datasheets and measured data govern the real result — confirm with a qualified engineer.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Use the free Solar Panel Degradation Calculator online — Forecast year-by-year output decline at 0.4–0.6%/yr and check production against the linear power warranty. Runs instantly in your browser: no signup, no upload, mobile-friendly.
About Solar Panel Degradation Calculator
Panels fade slowly — median 0.5%/yr per NREL's degradation studies — but over 25 years that compounds to ~12% lost capacity. Forecast your plant's year-by-year output, total lifetime energy, and whether measured production has fallen below the manufacturer's linear warranty line (a claimable event).
How to use Solar Panel Degradation Calculator
- 1Enter system size and keep or adjust the degradation rate (help text gives climate guidance).
- 2Set the horizon (warranties usually run 25 years).
- 3Read output at years 5–25, total lifetime energy, and compare measured production to the warranty line.
Why use Solar Panel Degradation Calculator?
- ✓NREL-median degradation rates with climate-adjusted defaults for hot regions
- ✓Year-by-year output and cumulative lifetime energy, not just a year-25 number
- ✓Direct comparison against linear power warranties — know when you have a claim
- ✓Region-correct first-year yield as the baseline
Frequently asked questions
How fast do solar panels actually degrade?+
Field studies (NREL's compilations) put the median at ~0.5%/yr for crystalline silicon — newer mono-PERC/TOPCon often 0.4%. Hot climates run 0.6–0.8%/yr. After 25 years, a healthy panel still produces 85–88% of its day-one rating.
When can I claim under a panel performance warranty?+
When measured output (corrected for irradiance and temperature) falls below the warranty's linear line — typically guaranteeing ~98% in year 1 declining to 84.8–87.4% at year 25. Document with a calibrated test or PR analysis across several months; one bad reading won't carry a claim.
Do panels fail outright or just fade?+
Mostly fade. Catastrophic failures (hotspots, glass breakage, junction-box faults) affect well under 1% of tier-1 panels per year. The economic question is the slow fade — which this forecast turns into yearly kWh so you can price it.
Does degradation change my payback period?+
Slightly. Most systems pay back in years 3–7, when panels still deliver 97–99% of rated output — degradation barely touches the payback. It matters for 25-year ROI and for sizing systems that must still cover a load in year 20 (off-grid, EV charging).
Embed Solar Panel Degradation Calculator on your website
Want Solar Panel Degradation Calculatoron your own site? Paste this snippet into any HTML page — it's free, with no API key or sign-up. The tool loads in an iframe and keeps working exactly as it does here.
<iframe src="https://tooljolt.com/tools/solar-degradation-calculator" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="Solar Panel Degradation Calculator — ToolJolt" loading="lazy"></iframe>Related tools
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