Path-Q Solar
How much production do solar panels typically lose as they degrade?
Answer
Solar panels commonly lose roughly 0.3% to 0.8% of output per year, with about 0.5% per year often used as a general planning estimate, rather than failing suddenly. The actual decline varies by module technology, climate, installation conditions, and the manufacturer's degradation specification, so the panel warranty and measured production are better guides than a single generic percentage.
Key points
- Degradation primarily reduces the panel's maximum output and can reduce annual energy production over time.
- Heat, ultraviolet exposure, humidity, cycling, and manufacturing differences can affect the rate.
- A sudden large drop is more suggestive of a fault, shading change, or soiling problem than ordinary degradation.
What it depends on
- Panel model and its warranted degradation curve
- Climate and operating temperature
- System age, shading, soiling, and equipment condition
- How production is measured and normalized for weather
Risks and trade-offs
- Comparing one year's raw production with another can confuse weather variation with degradation.
- Warranty limits may not match actual output under every operating condition.
- Degradation is gradual, so it may be difficult to distinguish from other small losses without consistent data.
Information you may need
- Panel model, installation date, and degradation warranty
- Weather-adjusted production history
- Any changes in shading, cleaning, inverter operation, or monitoring
Your next step
What to do next
Review the module's degradation specification and compare long-term, weather-adjusted production rather than relying on a single-month difference.
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