Most of our sources of energy are actually derived from solar energy. Consider fossil fuels, for example. They were formed by the decomposition of plants and animals. The animals got the energy stored in their body from plants. And the plants got their energy by trapping solar energy through photosynthesis. Figure 5.14 shows other such examples of energy sources derived from solar energy.
Besides making use of solar energy is in this way, we can also use it directory or heating and for producing electricity. However, though solar energy is abundant and renewable, it is diffused. In the following section we will see how solar energy is concentrated by different devices.
Solar heating devices solar cookers and solar haters are devices that utilize solar energy for cooking are devices that utilize solar energy for cooking and heating respectively. A solar cooker is a box made of wood. The inner side of the box is painted black so as to increase the absorption of heat. The containers inside the box are also painted black for the same reason. The box has a glass cover, which allows solar energy to enter and prevents heat from radiating out of the box. A plane mirror fitted to the top of the box reflects light into the box. Despite all these measures to concentrate. Solar energy and prevent the loss of heat, it takes a long time to cook with the help of a solar cooker. Besides, a solar cooker can only be used when it is sunny.
A solar heater consists of a coiled copper tube, which is painted black. The loops or turns increase the surface area and he color helps the absorption of heat. Water gets heated as it passes through the tube, which is place inside an insulated box with a lasso’s top. This devices supply hot water for domestic and industrial use.
Huge concave minors are used to focus the sunlight falling over a large area on to a point. This technique is used to design solar furnaces.
Solar cells a solar cell are an advice that converts solar energy into electrical energy. However, it can produce only a small amount of power, good enough to run gadgets like watches and calculators. A large number of solar cells are joined to form a solar pane, when a greater amount o power is needed. Te power generated is stored in a battery, which is connected to the appliance. Solar panel are used in artificial satellites, remote areas, villages, and even hotels and institutions. However, using solar panels to generate electricity on a large is still too expensive to be feasible.