Solar power tower. Electricity-generating solar power tower. 2000 mirrors (some at bottom) track the sun and focus its rays onto a receiver at the top of the centrally-located tower (white, upper centre). The receiver collects the sun's heat in a fluid which is used to produce steam. Steam- driven turbines then generate electricity. This tower is unique since it can store the sun's energy in molten salt and provides energy on demand. This is the Solar Two tower at the Barstow solar power plant, California, USA.