Finland has inaugurated an industrial-scale sand battery this week in the southern town of Pornainen, where it'll take over heating duties from an old woodchip power plant for the municipality. It's set to reduce carbon emissions from the local heating network by as much as 70%, and is the largest…
There are other methods, but they’re far less efficient.
Solar panels convert light, not heat, into electricity. Specifically, photons (light) excite electrons in the solar cell, and these excited electrons then move through the solar cell and form a current.
This isn’t really being used to generate electricity. They’re developing a generator from it, but currently it’s used for purely thermal energy transfer. Basically, the towns have big pipes running through them for communal heating, and these pipes are heated by this thermal energy storage.
I imagine they’re only talking about electricity generation as an extra revenue stream for their customers who buy these, rather than it being a good solution for storing and generating electricity. The 90% efficiency is much better than combustion generators, but far worse than true electric batteries.