Solar Water Heating System

• A solar water heating system consists of a flat plate solar collector, a storage tank kept at a height behind the collector, and connecting pipes.
• The collector usually comprises copper tubes welded to copper sheets (both coated with a highly absorbing black coating) with a toughened glass sheet on top and insulating material at the back. The entire assembly is placed in a flat box.
• In certain models, evacuated glass tubes are used instead of copper; a separate cover sheet and insulating box are not required in this case.

• The system is generally installed on the roof or open ground, with the collector facing the sun and connected to a continuous water supply.
• Water flows through the tubes, absorbs solar heat and becomes hot
• The heated water is stored in a tank for further use
• The water stored in the tank remains hot overnight as the storage tank is insulated and heat losses are small.

• At homes for producing hot water that can be used for bathing, cleaning, and washing.
• It can also be used for a variety of industrial applications.

• Most domestic solar water heaters are provided with electrical back-up.
• Electrical heating elements are usually placed in the storage tank and can be switched on during cloudy days.
• In some cases, the solar-heated water is led into an existing electrical geyser; the geyser needs to be switched on only in cloudy conditions.

The smallest solar water heater available has a capacity of 100 litres per day, which is sufficient for a family of four to five members. It costs Rs 15 000 to Rs 18 000, and can save about 1500 units of electricity per year.

• Solar water heating systems can be obtained and installed through manufacturers, their dealers, and ‘Aditya’ Solar Shops.
• Repair and servicing facilities are also available with them.
• The state nodal agencies also provide information on their availability.