Solar Water Heater comes under the broad category of Solar Thermal solution. Solar Water heater is very useful for domestic use as well as commercial users like hotels, hospitals, hostels, guest house. In comparison to an electric heater, it saving is huge because a normal 15 litre electric geyser comes with 2.0 KW electric heating element whereas the solar water heater consumes Zero electricity. As the sun is a day phenomenon the solar water heater is measured in Litre per Day (LPD). The smallest size available in the market is 100 LPD. As per industry norms one 100 LPD solar water is considered suitable for 4 person using same bath room (no distribution). The solar water heater is consisting of a collector and a tank which carries both hot and cold water. The insulated tank can keep it hot till next day with just a minimum overnight loss of 10 degree.
There are two types of collectors available in the market – Flat Plate Collector (FPC) and Evacuated Tube Collector (ETC). FPC is considered more durable while as ETC uses glass tubes it is fragile.