Solar (PV) Power

A solar panel is a semi-conducting diode that converts sunlight directly into DC electricity. It has a large flat surface area to absorb a maximum amount of energy from the sun. Solar panels are actually a series of photovoltaic cells connected to form an array. Each PV cell consists of six basic parts:

1. A thin metal grid

2. An anti-reflecting coating

3. A negatively charged silicon layer
(n-layer)

4. A positively charged silicon layer
(p-layer)

5. Contact plate

6. Mounting substrate

The p-layer and the n-layer are bonded together to form the a p-n junction. This junction only allows electrons to travel from the p-layer to the n-layer, not the reverse. The n-layer is on top and is coated with an anti-reflection coating to help it absorb sunlight. A thin metallic grid is attached to the top of this n-layer allowing it to be exposed to sunlight. The lower (p-layer) semiconductor is bonded to a metallic contact plate which is wired to the top metallic grid. The whole "sandwich" is attached to a plastic substrate for mounting.

When sunlight is exposed to the outer silicon layer (n-layer) excess electrons are "knocked" loose from the silicon. The electrons are attracted to the positive side of the cell. The metal grid collects the electrons and allows them to travel through a load to the positive semiconductor, thus forming an electric current. Since the current and voltage produced by each PV cell is small, many cells are connected in series and in parallel to increase the current and voltage. This is a solar module.

Benefits of Solar panels:

There are many benefits to using solar power.

It is the most common type of renewable energy.
Solar panels have no moving parts and are durable. Therefore they require little to no maintenance and are quiet.
Many panels can be connected together to produce as much power as needed for your home.
The power generated can be stored in a bank of batteries for later use. This simply requires a charge controller.

Solar panels have efficiencies between 10% and 15%. This means that they convert 10%-15% of the energy gathered from the sun into electric current. The remaining energy is converted into heat. They have a typical life of 25-30 years.

For more detailed information on how a solar panel works and how it is made click on the following link.

National Center for Photovoltaics: http://www.nrel.gov/ncpv/