This is too cool (or hot, I guess!) Storing solar energy, especially thermal energy, has always been a challenge. I love to see this innovative method of storing heat energy for solar cooking at night. One of the great challenges of solar pool heating is how to store excess energy during the day for continued heating at night. Right now there is no viable option.
Check the links. It's a complete fraud. As far as storage goes it's quite easy to store heat in water tanks.