Unfortunately I don’t know.
To correlate the effect with social processes, one would have to plot the same graph for multiple countries and see what processes occur in each history at the time of the lines forking apart (assuming they do so).
Some guesses: automation, perhaps globalization of supply chains, something related to the effectiveness of employees at bargaining with employers?
I have a solar panel that died. A piece or plywood flung by a storm went right through it, leaving a 30 cm “wound”.
Well, to be honest, it’s alive, just weaker - the panel remains suitable for pumping water on the field during muddy season. I wouldn’t take a good panel to such a bad place, but this panel, I have no worries about.
As for what happens when they really, really die - they get disassembled. The aluminum frame gets taken off and goes into metal recycling. Junction boxes go to where plastic goes - not a nice place. The glass and doped silicon go into a crushing mill, after which they get separated. The glass is easy to recycle, but the doped silicon is difficult to refine again to such a purity, so it likely won’t become a solar panel. But it’s a very small fraction of the panel’s mass.