Basics of Solar Cell

Solar energy is the ultimate source of energy, which is naturally replenished in a short period of time, for this reason it is called "renewable energy" or "sustainable energy" source. To take advantages of solar energy, the variety of technologies is used to covert solar energy to heat and electricity. The use of solar energy involves 'energy conservation' because it is the way to use energy source that comes from the nature and uses it more wisely and efficiently. That way includes Solar Cell, which is described as follows:

What is Solar Cell?

Solar Cell or Photovoltaic (PV) cell is a device that is made up of semiconductor materials such as silicon, gallium arsenide and cadmium telluride, etc. that converts sunlight directly into electricity. When solar cells absorb sunlight, free electrons and holes are created at positive/negative junctions. If the positive and negative junctions of solar cell are connected to DC electrical equipment, current is delivered to operate the electrical equipment.

Solar cell types
There are three major cell types that classified by its manufacturing technology and the semiconductor.

Single Crystalline Silicon PV Module	Polycrystalline Silicon PV Module	Amorphous Silicon PV Module

Solar cell structure
The most semiconductor material currently use for solar cell production is silicon, which has some advantages as; it can be easily found in nature, does not pollute, does not harm the environment and it can be easily melted, handled and formed into monocrystalline silicon form, etc. The commonly solar cell is configured as a large-area p-n junction made from silicon.

How solar cell works?

When sunlight strikes solar cell surface, the cell creates charge carrier as electrons and holes. The internal field produced by junction separates some of positive charges (holes) from negative charges (electrons). Holes are swept into positive or p-layer and electrons are swept into negative or n-layer. When a circuit is made, free electrons have to pass through the load to recombine with positive holes; current can be produced from the cells under illumination.

The individual solar cells are connected together to make a module (called 'solar module' or 'PV module') to increase current and the modules are connected in an array (called 'solar array' or 'PV array'). Depending on current or voltage requirement, solar arrays are connected in a variety of ways:

Solar PV system
Solar cells produce direct current (DC), therefore they are only used for DC equipments. If alternating current (AC) is needed for AC equipments or backup energy is needed, solar photovoltaic systems require other components in addition to solar modules. These components are specially designed to integrate into solar PV system, that is to say they are renewable energy products or energy conservation products and one or more of components may be included depending on type of application. The components of solar photovoltaic system are

Solar cell advantages
Solar cell or PV cell produces clean with non-polluting energy source of electricity that is environmental-friendly. Since it uses no fuel other than sunlight, gives off no waste, no burning, and no moving part when it operates. It reduces collection of gases such as carbon monoxide, sulfur dioxide, hydrocarbon and nitrogen, etc., which generated from fuel, coal and fossil fuel burning power plants. All decrease the impacts of energy on the environment like greenhouse effect, global warming, acid rain and air pollution, etc. It is easy to install and transportable. With the modular characteristic, it can be constructed any sizes as required. Moreover, it requires minimal maintenance and has long life span (more than 30 years) and stable efficiency.

Solar cell applications