Solar Water Heaters Hot water at 60-80 C for hotels, hospitals, restaurants, dairies, homes, industry
etc. Solar water heaters (SWHs) of 100-300 litres capacity are suited for domestic application. Larger systems can be used
in restaurants, canteens, guest houses, hotels, hospitals etc.
Fuel Savings: A 100 litres capacity SWH can replace an electric geyser for residential
use and saves 1500 units of electricity annually.
Avoided utility cost on generation The use of 1000 SWHs of 100 litres
capacity each can contribute to a peak load shaving of 1 MW.
Environmental benefits A SWH of 100 litres capacity can prevent
emission of 1.5 tonnes of carbon-dioxide per year.
Solar water heaters based on Flat plate Collectors (FPC based SWH) Here the solar radiation is absorbed by flat plate collectors which consist of an
insulated outer metallic box covered on the top with glass sheet. Inside there are blackened metallic absorber (selectively
coated) sheets with built in channels or riser tubes to carry water. The absorber absorbs the solar radiation and transfers
the heat to the flowing water
Solar water heaters based on Evacuated Tube Collectors (ETC based SWH)
Here the collector is made of double layer
borosilicate glass tubes evacuated for providing insulation. The outer wall of the inner tube is coated with selective absorbing
material. This helps absorption of solar radiation and transfers the heat to the water which flows through the inner
Subsidy and Incentives Though the initial investment for a solar water heater is high compared to available conventional
alternatives, the return on investment has become increasingly attractive with the increase in prices of conventional
energy. The pay back period depends on the site of installation, utilization pattern and fuel replaced. To offset
the high initial investment for solar water heaters, the Ministry is currently implementing a soft loan scheme
through seven designated banks and Indian Renewable Energy Development Agency (IREDA), which has now been extended
to all kind of Financial Institutions