Ultimately it's a semiconductor, so it's affected by the same aging processes that transistors and LEDs undergo. Actually, LEDs and solar cells are physically t

Ultimately it's a semiconductor, so it's affected by the same aging processes that transistors and LEDs undergo. Actually, LEDs and solar cells are physically the same component, just designed for opposite use cases - much like motors and generators. You can reasonably expect it to lose less than 1% of original efficiency a year, so they should last decades.