French photovoltaics group Hespul tested solar panels installed in 1992, reports PV Magazine:
The testing showed that the modules still produce on average 79.5% of their initial power after 31 years of operation. In a previous testing carried out 11 years ago, the panels were found to produce 91.7% of their initial power. “This result exceeds the performance promised by the manufacturers who said the panels would have maintained 80% of their output after 25 years,” said Hespul.
The drop in performance is on average 20.5%, or 0.66% per year over 31 years, and 1.11% per year over the last 11 years… Another more recent study carried out by the US Department of Energy’s National Renewable Energy Laboratory (NREL) on 1,700 American sites totaling 7.2 GW of power, showed a median degradation of around -0.75%/year. Moveover, another research study focused on 4,300 residential installations in operation in Europe and used different data processing methodologies. Depending on the methods, a median loss of -0.36% to -0.67%/year was obtained.
Thanks to long-time Slashdot reader storkus for sharing the news.