Gobind Power Solar Shimlapuri, Ludhiana, Punjab

Evacuated Tube Collector (ETC)   Why should one go for solar water heating? Because Solar water heaters save electricity and thus money, electricity is becoming more and more expensive, they could even turnout to be more reliable than electric power supply (at least in many parts of our country), they are clean and green and thus reflect one's commitment for preservation of environment, they are safer than electric geysers as they are located on the roof; and, if well designed, may even look good on the roof top of the house. Solar water heating is now a mature technology. Wide spread utilization of solar water heaters can reduce a significant portion of the conventional energy being used for heating water in homes, factories and other commercial and institutional establishments. Today in our daily living we need hot water for many applications. Not only for bathing it is required for other applications such as cleaning of house, utensils, washing of cloths, cooking and many other applications in home, hospitals, hotels and industries even for feed water to boilers at high temperature. Working of Solar Water Heating System The working of solar water heaters is very simple to understand. Two common phenomena observed in everyday life are the key to functioning of solar water heaters. These are, first, a black surface heats up when left in the sun, by absorption of solar radiation; and second, the inside of a car becomes very hot, if it is left in the sun with windows closed. A car becomes hot in sun because solar radiation can pass through the glass windows but cannot come out. It is trapped inside and thus heats up the car. The heat trapping principle is the famous Green House Effect. The good absorption property of black surfaces is used to improve solar energy absorption in a solar heater. These two phenomena are utilized in collectors of commonly available solar water heaters. A typical domestic solar water heater consists of a hot water storage tank and heat collectors. The collectors are glazed on the sun facing side to allow solar radiation to come in. A black absorbing surface (absorber) inside the collectors absorbs solar radiation and transfers the energy to water flowing through it. Heated water is collected in the tank which is insulated to prevent heat loss. Domestic solar water heaters work on the principle of thermosyphonic effect. Circulation of water from the tank through the collectors and back to the tank continues automatically due to density difference between hot and cold water. No electricity is required for circulation of water or for any other operation in such systems. However, in case a back up heater is provided to take care of hot water requirement during cloudy days, electricity will be required.