photovoltaic cells :: essays research papers

Photovoltaic cells ar solid state devices that convert sporting directly into electricity. Photovoltaic literally means light electricity. These devices can be commonly found providing power for small scale devices such as calculators, watches, and small radios. However, they atomic number 18 not limited to small scale systems. They ar also used to power satellites, communications equipment, houses and m both other things, peculiarly in remote locations where a power grid is not right away available. In isolated locations the only power attainable comes from the sun. The sun shines near 1000 watts of energy per square meter of the planets surface, which if harnessed could power any city. The commercial development of the photovoltaic cell took more then a hundred years to begin. A french physicist Edmond Becquerel first described the photovoltaic effect in 1839. At the age of 19 Becquerel found that authoritative materials when exposed to light adduced small measurable curr ents. Henrich Hertz also study the effect in solids in the 1870s and he managed to produce photoelectric cells with an skill of about 1%. In the 1940s the new Czochralski process made generating extremely pure crystalline silicon possible and furthermore made commercializing photovoltaic cells an option. Development really started however, in 1954 when Bell Laboratories used the Czochralski process to produce a 4% efficient crystalline silicon cell, which was essentially for finish in space. This was the beginning of photovoltaic cells. Photovoltaic cells generally consist of tail fin layers. Two of these layers are semiconductors and the remaining three are but for security measures and to aid absorption of light. The round top layer is generally a fruitcake cover for protection against the elements since photovoltaic cells are used outside. Underneath this is an anti-reflective coating. Since well-nigh photovoltaic cells are made of silicon and silicon is reflective this prevents the photons from merely being bounced off the cell and allows the highest amount of absorption possible. These two layers are secured with a transparent adhesive. Transparent, obviously, so the photons can pass through it. environ the entire cell is a metallic grid on top and a metal contact on bottom. The two layers of semiconductor are the most important. Semiconductors are materials that have electrical conductivity intermediate amongst the high conductivity of metals and the low conductivity of insulators. Conductivity is decided by how many free electrons are available to carry charge, and in loose how tightly electrons are bound to the parent atom.