Solar modules deployed in France in 1992 still provide 79.5% of original output

storkus writes:

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

Another US NREL study says ~0.75% per year. Locally here in Arizona there are a LOT of used panels available at VERY cheap prices, but CSA / UL / NFPA may be the reason they go uninstalled.