You'd be surprised

a) how common solar panels are (and how easy it is to partially repair broken solar panels)

b) how simple they are to make if efficiency doesn't matter (optional glas + conductive grid + any black isolator + aluminum foil will result in power delivered between the grid and the aluminum. Paper (even white laser printer paper frankly) will do fine as isolator, also I heard balloon plastic works very well. Of course a transparent conductor works way better than a grid (which is where 80% of the efficiency comes from), but it works at like 5-10% efficiency with a grid) (the optional glass is to keep it clean, you can of course also just clean it regularly)

c) how long batteries last if you only ever use 5% of their capability