Actual usable lifetime is significantly longer. There's a good compendium of information here: https://www.nrel.gov/pv/lifetime.html https://www.nrel.gov/pv/li

Actual usable lifetime is significantly longer. There's a good compendium of information here: https://www.nrel.gov/pv/lifetime.html https://www.nrel.gov/pv/lifetime.html If you want to do a deep dive, the open preprint of "Photovoltaic Degradation Rates: an Analytical Review" is a good start: https://www.nrel.gov/docs/fy12osti/51664.pdf https://www.nrel.gov/docs/fy12osti/51664.pdf It's from 2011 so is a little dated, but later studies have found about the same degradation rates. It's good because it uses data from large numbers of real-world solar installations. Most degradation studies are reporting on only a small number of modules and/or use artificial accelerated aging conditions. The median degradation rate for crystalline silicon PV modules was found to be 0.5% per year. This would imply more than 40 years for the median module performance to decline to 80% of original rated output. I personally use 30 years as a more conservative rule of thumb, especially since modules appear to follow a degradation "bathtub curve." But it is clear from field data that the median solar module produces useful power levels far longer than 10 years. I suspect that modules designed for durability can achieve median lifetimes over 50 years.