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 tube.
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.