Re: Interesting idea
Molten salt is used for this purpose already, have easily handled temperature ranges and being plentiful (near the sea). Silicon heat storage involves much higher temperatures - so harder engineering - but is more efficient as a result.
Salt has a virtuous benefit; with available energy you can get the salt by desalinating sea water. The salt goes into your heat store, enabling the generation of electricity, and the fresh water is likely a valuable resource in hot, permanently sunny areas suited to solar-salt energy schemes.