Solar Power Towers
Instead of using photovoltaic panels to convert sunlight into electricity, a solar power tower is a type of solar furnace. An array of mirrors concentrates sunlight on a central tower and the heat is used to provide power, similarly to more conventional generators.
Early designs used the solar thermal energy to heat water, producing steam, which was used to drive turbines. Newer designs use liquid sodium or molten salts (similar to the way some nuclear plants work). These liquids have high heat capacity, meaning they can store a lot of thermal energy. This stored heat can then be used to boil water and drive steam turbines, with the added benefit that enough heat can be stored to keep generating power even after sunset.
One of the leading organisations developing this technology is a Spanish company, Abengoa Solar.