12-12-2012, 11:43 AM
HOW A SOLAR (PHOTOVOLTAIC) CELL CONVERTS SOLAR ENERGY TO ELECTRICITY
HOW A SOLAR (PHOTOVOLTAIC).pdf (Size: 181.29 KB / Downloads: 92)
Introduction
Most solar cells (photo-voltaic cells,
or just pv-cells) are made of
crystalline silicon. Silicon occurs
naturally as silicates in many rockforming
minerals and in ordinary
beach sand. However the silicon
needed to make a pv-cell must be
very pure and perfectly crystalline.
The silicon atom has four electrons in
its outer, valence shell. In a crystal, all
four of these electrons are used in
forming co-valent bonds to
neighbouring atoms. Most metal
atoms, on the other hand, have only
one or two outer electrons, and in the
solid state these electrons are
relatively free from their parent
atoms, and can move through the
crystal, as “conduction electrons”.
Metals can therefore conduct
electricity quite easily, while silicon is
normally an insulator.