Solar water heater is solar equipment which works by harnessing the heating capacity of the sun. It utilizes the principle of thermal conversion thus making the water to boil.
Solar geyser consists of two parts, the flat plate collector and the insulated water tank. An evacuated tube connects the flat plate collector and the water tank. The flat plate collector is a box made of wood or metal and the inner walls are painted black to maximize the heat absorbing capacity. A thick glass lid covers the collector to allow heat into it and prevents escaping of heat.
The water storage tank stores both hot and cold water. This is also insulated and metallic. The tank has water inlet and outlet valves. A coiled tube which connects these two parts is usually made of copper. It is painted black on the outer surface. The heating of the water takes place in the collector tube. Both the function of inlet and outlet is served by the copper connector tube. Cold water enters the tank and hot water leaves the tank via this tube. The water outlet from the storage tank connects to the water taps via water outlet pipes.
The copper tube brings in fresh water into the storage water tank. This water enters the collector tube and circulates through it. As the collector is covered by the glass plate, maximum heat and light enters through its surface. This is absorbed by the black surface of the tube. Thus the heating of the water inside the tube is initiated. As the water gets heated, it continuously leaves the collector and enters the storage tank. Hot water being lighter floats on the top layer of the storage tank. The storage tank has an outlet valve in the upper part and thus hot water is supplied into the pipes via this outlet. Fresh cold water being heavier stays in the lower part of the geyser and is led into the collector via the tube. The water circulation is self maintained in a solar geyser.
The heating capacity of the solar geyser depends on the suns power at that particular time and place. It is best used in tropical areas. The greater the area of heat entering, the more will be the efficiency of the device. The number of evacuated tubes and flat plates used in the construction of the solar heater also greatly affects its efficiency.
Solar water heaters are cost efficient. They have a better life span than the conventional water heaters. In cold areas, freeze protection should be used and this is costly. With the advent of Do-it-yourself kits and guides, people are now increasing making their own sun powered water geysers. These can be made from simple low cost accessories. There arises no question of installation cost while setting up one's own solar heater.
