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Solar Thermal Energy
Solar thermal energy:
Solar energy panels are used to collect solar energy for heat; this is very different than solar photovoltaic, which converts solar energy directly into electricity. Solar thermal panels have different classifications by the US Energy Information Agency; the three different classifications are low, medium and high temperature collectors. Low temperature collectors are flat plates generally used to heat such things as swimming pools. Medium temperature collectors are used for creating hot water for residential or commercial use. High temperature collectors concentrate the sunlight using mirrors or lenses and are generally used for electric power production. Common uses for all three types of solar thermal panels include heating, drying and water distillation.
The first of the three most common uses for solar energy panels which is water heating is the most common and widely used especially where there is high solar isolation (the total energy per unit area received from the sun.) Domestic water heaters are usually found amongst wealthier sections of the communities in developing countries. There are a wide variety of solar water heaters available on the market today. Many of the solar water heaters available consists of a series of pipes that are painted black, sitting inside an insulated box fronted with a glass panel. This is the solar energy panel which is the collector; the fluid that is heated by the sun is then circulated through the tank several times to raise the heat of the fluid to the required temperature.
The second of the three most common uses for solar energy panels is solar drying. Controlled drying is necessary for various types of products and crops including grain, coffee, tobacco as well as some fruits, vegetables and fish. Many times drying is done to enhance the quality of the product. Solar thermal energy is used to assist in the drying of such products. The heat of the product is raised and at the same time air passes through the compartment to remove moisture. The flow of air is often promoted using a method referred to the stack effect which maximizes the fact that hot air rises and therefore drawn up the “stack” pushing cool air downward. Doing this to crops can improve and protect the beneficial effects of the health and nutrition of the crop.
The third of the three most common uses for solar energy panels is distillation or desalination. A basic solar thermal energy “still” can be used to purify drinking water in remote regions where needed removing impurities such as fluoride and salt. This is done so by placing a glass or transparent plastic cover over a shallow tray of water which has a black backing to trap the solar energy. When the sun heats the water up it evaporates which then condenses on the underside of the glass covering, this covering is at an angle so water drains off and the impurities are trapped below, thus providing clean drinking water.
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