Désirer est-ce nécessairement souffrir

Pages: 4 (796 mots) Publié le: 26 avril 2010
The Photovoltaic

History:

The photovoltaic effect, which is the transformation of solar energy ("photon") into electricity ("Volt") was discovered in 1839, by the French physicistA.E.Becquerel.
Its use in industry only began in the 1960's, mainly for space industry applications.
Then, in the 1970's to others applications have been invented to respond initially to industrial needs,but eventually to the isolated spaces.
The current context is in favor of photovoltaic. The photovoltaic solar energy is able to meet a growing demand for renewable energy. It is considered to play asignificant role in world energy supply. This one will be even greater and more rapid than the methods to produce solar electricity at lower cost will be used. Unlike other renewables, the solarenergy is available everywhere on earth. Europe has a productivity average daily 3kWh per square meter while the deserts sunniest collect 7kWh.

Principles:

The solar photovoltaic panels are madeof 5 layers of cells composed of silicon .The first layer is composed of glasse, the second layers is silicon and it is used as an anti-reflection coating, the third is a gate driver. The fourth andfifth layers produce the electricity and there is an other layer who is a conductive metal. These cells are exposed to light (photons) that simultaneously generates two types of phenomena: a voltageand current. Installed on rooftops, solar photovoltaic panels are connected to an inverter that allows the issuance of voltages and currents. To obtain an electric current, we must introduce an electricfield, on both sides of the cell.
The method used to create this field is that of "doping" by impurities.
Two types of doping are possible:
Doping n-type (negative) is introduced into thecrystalline structure semiconductor atoms that have foreign ownership to give everyone an excess electron (negative charge), free to move within the crystal. This is the case of phosphorus (P) in silicon...
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