Electrical
Degradation Rate
Summary
Annual percentage decrease in solar module power output over its lifetime.
Detailed Explanation
Solar modules gradually lose power over their 25-30 year lifetime. Typical rates in 2026: Tier-1 TOPCon 0.4%/year first-year 1%; Tier-1 PERC 0.55%/year first-year 2%; Tier-3 modules can degrade 1-2%/year. A 30-year linear warranty of 85% at year 30 implies 0.43%/year average. Light-Induced Degradation (LID) causes rapid first-year drop; Potential-Induced Degradation (PID) causes long-term failures under high voltage + humidity. Always choose modules with PID-resistance certification.
Further Reading
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