Solar Photovoltaic Cell - Close up
How a Solar PV Cell works (detailed):
1) A PV cell consists of two thin layers of semi-conducting materials, usually silicon.
2) One silicon layers is ‘doped’ or treated with tiny amounts phosphorus , which causes free charges in that layer (negative), and the other layer is doped with boron which causes a lack of charges or ‘holes’ (positive).
3) Once in contact, the excess charges of the negative-type layer and the lack of charges ‘holes’ in the positive layer, migrate towards the opposite layers, and thus create an Electric Voltage difference across the junction at equilibrium. This is termed a p-n junction, and forms what is known as a diode or photo-diode.
4) Photo-Electric Effect: When incoming solar radiant energy strikes the negative side of the junction, it excites an electron, thereby creating a free electron (and a positively charged electron hole). This mechanism is also known as the inner photoelectric effect. If the absorption occurs near the depletion region, these carriers are swept from the junction by the built-in field of the depletion region. Thus holes move toward the anode, and electrons toward the cathode, and a photocurrent (Electricity) is produced.
