Solar air conditioning refers to any air conditioning (cooling) system that uses solar power. This can be done through passive solar, solar thermal energy conversion and photovoltaic conversion (sunlight to electricity). The principle behind solar driven conditioning is similar to conventional conditioning in that the cooling is produced through the evaporation of some form of liquid refrigerant that absorbs the heat and cools its surroundings. The difference here is that solar thermal energy is used instead of electrical power as the driving energy.