SOLAR CELLS

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A solar cell has a size of 5 x 5 inch or 6 x 6 inch and a thickness of around 220 to 270 μm. A solar cell is made of semiconductors, mainly silicon. There are polycrystalline and monocrystalline silicon solar cells.

Basically, when light strikes the cell, a certain portion of it is absorbed within the silicon. This means, the energy knocks electrons loose, allowing them to flow freely. Each solar cell also has an electric field, which acts to force electrons freed by light absorption to flow into a certain direction.

This flow of electrons is a current, and by placing metal contacts on the top and bottom of the PV cell, that current can be drawn off to use externally. This current, together with the cell's voltage ( which is a result of its built-in electric field ), defines the power ( or wattage ) that the solar cell can produce, measured in Wp ( Watt peak ).

Depending on the cell temperature and insolation, the power measured in Wp at STC is the so-called power of the Maximum Power Point ( MPP ).