I wish I still had the link but I believe that the very first solar cells are still producing power at about 50% of original capacity more than 50 years later. It would be interesting to plot loss of rated power over time and see if it's linear or a curve. If on a curve, those things might produce 30%-50% of original rated power for a century or more, but I don't know anywhere to find such data.
Would it be possible to recycle PV? It could be a much better deal in terms of energy payback.