The heat from the sun can be used to provide hot water. The simplest way of heating the water is to have it flowing in tubes which are exposed to sunlight. These tubes are enclosed in a flat box called a solar water panel which can be mounted on the roof.
The infra-red component of sunlight induces heating when it strikes an absorber. If the absorber is a series of tubes in which water flows, then this solar heat is transferred to the water producing solar water heating.
As a typical panel is 2 metres long by 1 metre wide, such panels are easiest mounted on the roof of a building if it is favourably orientated to receive sunlight during most of the day.
The advantages of solar water heating are:
- the only external energy required is to pump the water through the solar collector
- captures energy from sunlight which otherwise would not be utilised
- negligible environmental emissions
- depending upon location. can produce up to 60% of hot water needs
- possible visual impact on surroundings
- less hot water in winter than summer
- output dependent on weather conditions