Power storage on the dark side

Sweden has a cement battery. Load-bearing structures are of interest generally; this one's a bit more constrained as it has to sit in one place.

That helps best, I think, where energy costs run higher when it's darker. Those would be the poles, here. And on the lunar night which is 14 days and frozen-cold. And on Mars.

All these places are probably better off underground not least because of ultraviolet during the daylight hours (or days); still, some structures will be out in the open, like telescopes and rover-garages. They'll want power.