The structure of a typical PV cell. PV cells are electronic devices made from semiconductor material. The material most commonly used is ultra-pure silicon. The deliberate addition of very small amounts of impurity gives the silicon special electronic properties, creating material known as p-type or n-type material. P-type material is usually created by the addition of boron, while phosphorus will create N-type material.
At the junction of p- and n-type regions, an in-built voltage is formed. This is not a voltage that can be directly measured with a meter, but it does affect free electrons present in the cell. When light strikes the silicon, it will penetrate a short distance until it is absorbed. The energy of each photon of light either creates heat and / or energizes an electron which is then released and able to flow as an electrical current. The in-built voltage pushes the electrons towards the top contact, where they are collect. Likewise the "holes" where the electrons came from are pushed towards the rear contact. An electric current can then flow if a circuit is made between the two contacts.
Photovoltaic devices or solar cells are like generators that work in sunlight. They produce elcetricity without combustion. They make electricity without waste, noise or pollution. A solar cell is a solid state device in which there are no moving parts (except for photons and electrons) so nothing wears out.
The fuel is "photon". these can be thought of " as packets of sunlight ". That carries a phenomenal amount of energy to earth at a prodigious rate.
ENERGY CONTENT OF SUNLIGHT
Sunlight has an energy content of 1Kw (1000 watts) per square metre . The typical solar panel achieves between 10% and 20% conversion.
NATURES WARRIORS GOALS FOR SOLAR ENERGY
… is to place 50 times 200 watt solar modules on the roof of every new home in Australia /http://cybercentre.greenpeace.org/