Photovoltaic (PV) technology makes use of the sun's abundant energy, and it has little impact on our environment. Photovoltaic can be used in a wide range of products, from small consumer items to large commercial solar electric systems. Commonly known as solar cells, individual PV cells are electricity-producing devices made of semiconductor materials. They are often connected together to form PV modules which then connected together to form PV arrays of different sizes and power output. The size of an array depends on several factors, such as the amount of sunlight available in a particular location and the needs of the consumer. The modules of the array make up the major part of a PV system, which can also include electrical connections, mounting hardware, power-conditioning equipment, and batteries that store solar energy for use when the sun isn't shining.
The PV effect is the direct conversion of solar energy into electricity. This process does not generate heat like solar domestic hot water or solar pool heating systems do. It also differs from the process used in solar thermal power plants, where concentrated solar energy is used to produce steam that activates a turbine connected to an electric generator. PV power systems do not have any moving parts. They are reliable, require little maintenance and generate no noise or pollutants. PV systems are modular - the building blocks (modules) come in a wide range of power capabilities, from a fraction of a watt (e.g. solar watches and pocket calculators) to more than 300 W. Modules can be connected to achieve the power that your application requires.
PV systems are classified into two, off-grid and on-grid. The off-grid system in an autonomous system that operates independent from municipal or the local electric company while the on-grid is usually connected to the municipal or local electric supplier, thus making the private PV an integral part of the national grid. Customers with on-grid PV systems can usually sell the excess electricity generated by their solar system to the local electric company. From the cost point of view, on-grid systems cost more to install due to the additional equipment needed to integrate the PV into the grid