Solar water heater

June 15, 2009

What is a solar water heater? It has a collector, which collects solar energy, and it has an insulated storage tank, which stores hot water. Solar water heaters can be of two main types, depending on the collector system, the first type is the Flat Plate Collectors. In this, the flat plate collectors absorb the solar radiation, they are made up of an insulated outer metallic box, which is covered by a glass sheet on the top. Inside, the blackened metallic absorber sheets have built in channels, or riser tubes, which the function of carrying water. The solar radiation is absorbed by the absorber, and the heat is transferred to the flowing water.

The second type is the Evacuated Tube Collectors. The collector is constructed through double layer borosilicate glass tubes, these are evacuated for the purpose of providing insulation. The inner tube’s outer wall is coated with selective absorbing materials. This assists in the absorption of solar radiation, and thus the heat is transferred to the water, which is flowing through the inner tube.

Using solar water heaters will help to benefit the environment, as the technology is quite mature today, having undergone much research. People can stop using conventional forms of energy for heating water in factories, residential homes, and other commercial establishments. The market for solar water heaters, too, has been steadily increasing. Solar water heaters can provide hot water at temperatures of 60-80 degrees, for restaurants, hospitals, homes, etc. The heaters which have a capacity of 100-300 liters, are quite suitable for domestic applications. However, one can install the larger systems in guest houses, hotels, etc.

So what about the fuel savings? Well, you’ll be astonished to know that a solar water heater of 100 liters capacity can replace even an electric geyser, and 1500 units of electricity are saved every year! And what about the environment? The solar water heater (of 100 liters capacity) prevents emission of 1.5 tonnes of carbon dioxide annually. The life of a solar water heater is approximately 15-20 years. The beginning investment for a solar water heater is somewhat high, initially, compared to more conventional fuel alternatives, but the returns on the investment are quite good, because prices of conventional forms of energy are rapidly rising. The period of payback, however, depends on many factors. These are the pattern of utilization, the fuel replaced, and the site of installation.

Solar water heaters are really easy – they are made up of thermal collectors which are covered with dark glass, and a fluid system that allows the heat to move from the collector to the point of usage. Lastly, there is a reservoir that stocks the heat water for its use. Such systems can be used to heat swimming pools, or for domestic purposes. Solar water heaters use solar power to give thermal energy in order to provide hot water. Such systems can save lots of energy, as well as cutting down on utility costs. Plus, the energy produced is absolutely clean. Even in the northern climate, with a cold winter sun, solar water heaters can bring a 40% reduction in the electric bill.

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