I thought you guys would find this interesting:
Stable Way to Store the Sun's Heat: Storing Thermal Energy in Chemical Could Lead to Advances in Storage and Portability
This compound goes through a molecular change when it is heated in the sun, storing the heat energy and storing it indefinitely. When a small amount of heat is applied, it reverts back to its original state and gives up its heat. It can get as hot as 200 C. Now they just need to make a similar compound with inexpensive materials.