Hot water heated by the sun is used in many ways. While perhaps best known in a residential setting to provide domestic hot water, solar hot water also has industrial applications, e.g. to generate electricity.[1] Designs suitable for hot climates can be much simpler and cheaper, and can be considered an appropriate technology for these places.

In order to heat water using solar energy, a collector, often fastened to a roof or a wall facing the sun, heats working fluid that is either pumped (active system) or driven by natural convection (passive system) through it. The collector could be made of a simple glass-topped insulated box with a flat solar absorber made of sheet metal, attached to copper pipes and dark-colored, or a set of metal tubes surrounded by an evacuated (near vacuum) glass cylinder.