This does seem like a prett niche solution because the electricity is converted into heat and then just used directly as heating - which removes a lot of the utility of electricity.

It is a great solution for places where heating is the primary use of electricity and I hope it finds broader applications.

Roughly a quarter of global energy is directed towards industrial heating. There are many "hot rocks" companies who have been commercializing ways to time shift cheap/free daily solar to night or even longer stretches.

I personally like Rondo's pitch[0] which is stacking concrete bricks into "heat batteries".

[0] https://www.rondo.com/