Photovoltaic cells, also commonly referred as Solar cells, are increasingly becoming common as an alternative source of utility power. They convert sunlight directly into electricity (direct current) with the help of semiconductor diodes. There are few Photovoltaic cells that can even convert infrared (IR) or ultraviolet (UV) radiation into DC electricity. Solar powered calculator is a common typical example that displays practical use of photovoltaic cells in our day-to-day life. Since these calculators use very small amount of electrical power, they are good enough to be used even in rooms with artificial lights.
Photovoltaic cell gets its name from the process it follows to convert light (photon) to electricity (voltage) and is called PV effect. In 1954 scientist at Bell Telephone discovered that silicon (an element abundantly found in sand) creates an electricity charge when exposed to sunlight. Harnessing the capabilities of PV effect, soon solar cells were developed to power space satellites and small items such as calculators and watches.
Today several thousands of people power their houses and business through individual solar PV system. In many countries PV system is used even for large power stations. Solar panels are made of solar cells combined into modules. Each module typically consists of around 40 solar cells. On an average 10 to 20 solar panels are required to power a house.
Photovoltaic cells are made of silicon which is in the form of flat plates. Silicon is a semiconductor of electricity. Impurities such as boron and phosphorus are added to the base materials to create an appropriate environment to free up the electrons when sunlight hits the photovoltaic panels. Electric is generated as the electrons get freed up. Due to the semiconductor nature, the electrons are forced in one direction creating electrical flow. These electrons travel through electrical circuit and are either used to power electrical devices or is sent to the grid. PV devices are commonly used today for variety of purposes from powering road side signs to homes to even large commercial businesses.
Severely hit by energy crisis in 1970, the world witnessed a major shift of interest in using solar cells for domestic as well as commercial use. However the growth was much restricted majorly due to high prices (roughly 30 times of the current cost of solar cells) rendering large scale commercial production impractical. Research and development combined with mass scale production led to sharp decline in cost of solar cells made the use of PV devices more feasible in the coming years. Installation costs of solar cells have also gone down, since with time number of experienced and trained installer have gone up. Several countries such as US, Germany, Spain and Japan have placed strong emphasis on strong national policies to promote shift is energy use from foil fuels to solar.
Majority of photovoltaic cell that we see around toady are either made of crystalline silicon or thin-film semiconductor material. Silicon cells are highly efficient in converting sunlight to electricity but are more expensive to manufacture. On the other hand thin film materials have lower efficiencies, but they are less expensive to manufacture.