The cost-prohibitive portion of this, which is greatly glossed over in the article and which I showed in my other reply - is that the steam generator required to recover this heat as electricity, is a massive part of the capex - more than half of the entire system end-to-end, including the solar and dirt storage. That makes the economy of it far less viable even with nearly free solar, which we're still quite far from.

This isn't true for high latitude areas, where the overprovisioning that would be needed for solar to work in winter would be massive. This is one of the markets he discusses.

This scheme, if it works, makes PV work great in Alaska.