The Ticino Solare solar power plant has been generating power every day for almost 40 years! Solar panels have no moving parts which mean they typically continue working for a really long time.
Today's manufacturing techniques for solar panels are far more robust than they were 40 years ago, so nobody really knows how long they will last beyond their 25-year product warranty.
Solar cells do degrade over time but once they get down to 80% of their original rating, which takes about 25 years, the degradation plateaus, as these 40-year-old panels generating at 80% of their original rating proves.
Read more at the link. https://www.pveurope.eu/solar-modules/switzerland-solar-plant-has-been-supplying-solar-power-40-years