[Linus]

The italian scientist Rubbia stores heat with the heat fusion of some salts.
This salts have always the same temperature and they assure always the same power.
He uses mirrors.
I think that a great solar furnace excavated in the land closed with a top cap is the best idea to utilize solar heat, it has no problem with wind and dust.

[Ludi]

Some success has been had using large solar reflectors to focus heat on Stirling engines. This doesn't store the heat of course but uses the sun to power an engine.

[Linus]

The sun's heat is not constant, this is the reason to store its heat.
The sodium chloride stores 490 kj/kg through its heat fusion, it stores 313 kwh(heat)/m3 that is more than 100 kwhel./m3.
It's a good solar storage......