This also means that when PV costs finally flatten out, there's a final cost reduction to be had from uncompressing their lifespan to the 40+ years nuclear is already counting on.
The reason you replace solar panels after 20 years rather than 40 is that they degrade and stop producing as much power. There is no option to run them for 40 years at their original generation capacity. The alternative is to keep using the old panels but add more panels on top of that to make up the difference. But then you still have to buy some new panels and on top of that you need to use more land instead of reusing the existing land, which may not be any cheaper than reusing the existing land by replacing all of the old panels.
And the cheaper the panels get the shorter their lifespan gets because the point when the generation loss from older/degraded panels exceeds the replacement cost comes sooner. It doesn't suddenly get longer when the price flattens out, it just stops getting any shorter than it already is by that point.
