Thermal sand batteries are a thing, I think?

That was some solution talked about on Undecided.

Gravity Batteries? They're much, much easier using water compared to solid masses.

You could store solar energy as heat in sand and use turbines(if you have water) or Sterling Engines(if you don't) to spine a generator. Peltiers are a solid state method to convert heat to electricity, but they aren't very efficient.