I know I might be late but I have a suggestion for their quirk.
Quirk- solar powered
The user can absorb energy from light and use it.
No light= no power
The user can use this energy in its raw form or in other forms, ex- fire, light, etc.
Bad overuse of quirk can cause radiation poisoning. The user can manipulate and shape raw energy to form objects or weapons.
This quirk requires a lot of concentration