Energy & Power  Tags: environmental_science oil coal nuclear wind water hydro power alternative energy solar geothermal  

Sunlight that reaches the ground consists of nearly 50 percent visible light, 45 percent infrared radiation, and smaller amounts of ultraviolet and other forms of electromagnetic radiation. This radiation can be converted either into thermal energy (heat) or into electrical energy, though the former is easier to accomplish. Two main types of devices are used to capture solar energy and convert it to thermal energy: flat-plate collectors and concentrating collectors. Because the intensity of solar radiation at the Earth's surface is so low, both types of collectors must be large in area. Even in sunny parts of the world's temperate regions, for instance, a collector must have a surface area of about 40 square metres (430 square feet) to gather enough energy to serve the energy needs of one person.

Source:

"solar energy ." Encyclopædia Britannica. 2009. Encyclopædia Britannica Online. 9  July  2009  <http://search.eb.com/eb/article-9068559>.

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aflorsm (Flickr.com, Creative Commons Licence)