Well, low intensity heat. It's trivial to create a setup where you take your hot morning shower with water heated in last noon's solar surplus. Setups like that are actually not uncommon at all, but they use direct solar heat extraction instead of photovoltaics. But a "bitcoined" version would be way too small scale and idle way too much to ever make back the hardware expense, at least unless progress suddenly stops.

Granted, it could still provide value beyond hot water: if you happened to own a considerable amount of bitcoin, your net worth would benefit from a greenwashing strawman giving bitcoin some more press attention.