Strangely, hail can smash up the glass covering the photovoltaic cells and they will still work. I worked at a sporting clays range and the trap batteries were kept charged by solar panels. A couple were on the end of errant shotgun blasts from 30 or so yards. The glass was cracked all over but it still output the normal voltage.
I image once the glass layer is compromised to further weathering, the electronics will start to deteriorate.
Not an expert by any means but seems likely.