Working Of a Solar Water Heater
The Sun’s rays fall on the collector panel (a component of solar water heating system). A black absorbing surface (absorber) inside the collectors absorbs solar radiation and transfers the heat energy to water flowing through it. Heated water is collected in a tank which is insulated to prevent heat loss. Circulation of water from the tank through the collectors and back to the tank continues automatically due to thermo siphon system. Based on the collector system, solar water heaters can be of two types: A solar water heater consists of a collector to collect solar energy and an insulated storage tank to store hot water. The stored hot water can be used later any time.
Main Components Of Solar Water Heating System
Main components of solar water heater system are
- Solar Collector( to collect solar energy)
- Insulated tank (to store hot water)
- Supporting stand
- Connecting pipes and instrumentation etc.
Applications Of Solar Water Heater
Water heating is one of the most cost-effective uses of solar energy. Every year, several thousands of new solar water heaters are installed worldwide. Solar water heaters can be used for Homes, Community Centers, Hospitals, Nursing homes, Hotels, Restaurants, Dairy plants, Swimming Pools, Canteens, Ashrams, Hostels, Industry etc. Use of solar water heater can curtail electricity or fuel bills considerably.
Usage of solar water heater for any application where steam is produced using a boiler or steam generator can save 70-80% of electricity or fuel bills. A residence can save 70-80% on electricity or fuel bills by replacing its conventional water heater with a solar water heating system. Solar water heaters are known to have the fastest repayment of investment in 2 to 4 years depending upon use and fuel replaced.
Types Of Solar Water Heater
Basically two types of solar water heater are available in the market
- Flat Plate solar water heater – Solar radiation is absorbed by flat plate collectors which consist of an insulated outer metallic box covered on the top with glass sheet.
- Evacuated Tube Collector – The Collector is made of double layer borosilicate glass tubes evacuated for providing insulation.
Flat Plate Collector (FPC) Solar Water Heater
A black absorbing surface (absorber) inside the flat plate collectors absorbs solar radiation and transfers the energy to water flowing through it. Bureau of Indian Standards has standardized this type of solar collectors in IS 12933; 2003.
Evacuated Tube Collector (ETC) Based Solar Water Heater
An ETC 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. However, these types of collectors have not been standardized and are sourced from the suppliers who have been empaneled by the Ministry of New & Renewable Energy/Government of India on the basis of performance testing of sample system.