What Are Photovoltaics?
As mentioned above, Photovoltaics (fo-to-vol-ta-iks) are one form of solar energy. Photovoltaics refer specifically to the practice of converting the sun’s energy directly into electricity using photovoltaic cells. Photovoltaic cells are often referred to as PV cells or solar cells. The term “photo” comes from the Greek “phos,” meaning light. “Voltaic” is named for Alessandro Volta (1745-1827), a pioneer in the study of electricity for whom the term “volt” was named. In 1839, Edmund Becquerel noticed that the sunlight absorbed by certain materials can produce, in addition to heat, small quantities of electricity. This curious phenomenon was limited to measuring light levels in photography until the 1950s. Then, improved purification techniques, advances in solid-state devices, and the needs of the emerging space program led to the development of photovoltaic cells. Photovoltaic cells convert sunlight directly into electricity; they have no moving parts. When sunlight strikes a PV cell,
Photovoltaic devices, or solar cells, convert sunlight directly to electricity. It is an attractive alternative to conventional sources of electricity for many reasons: it is silent, non-polluting, and renewable; it requires no special training to operate; it is modular and versatile; it is extremely reliable and virtually maintenance free (with no moving parts); and it can be installed almost anywhere. The customer pays only for the system; the fuel is free. Photovoltaic cells are made of a semiconductor material, usually silicon, and produce an electric current in the presence of light. Individual cells are combined to create modules that produce a specific amount of peak power. The modules, in turn, can be combined to create arrays that produce larger amounts of power. These arrays can be sized to meet the power requirements of the particular application.
A. Photovoltaics (PV), also known as solar cells, are semiconductor photodiodes that convert light energy to electrical energy. Photodiodes have positive and negative sides, like a simple diode, that allow electrical current to only flow in one direction. Electrons are released from one side of the photodiode when light of sufficient energy is absorbed by the semiconductor material. These electrons are available to flow through an external circuit and return to the opposite side of the of the photodiode. Electrons are prevented from flowing internally to the opposite side because of diode characteristics of the device. This unidirectional action is what allows current flow only through an external circuit. Outside our atmosphere, in space, light from the sun shines with a power of 1,350 watts/m2. On a clear, sunny day, the power of the sun at the earth’s surface regularly exceeds 1,000 watts/m2. You can gauge the magnitude of 1,000 watts in terms of the power required for a small elect
Photovoltaic technology (PV) uses solar cells to convert sunlight directly into electricity. PV modules consist of semiconducting material that absorbs sunlight in a way that frees electrons from atoms. Electricity is produced as the electrons flow through the semiconducting material. A group of PV modules are typically combined in an array to generate electricity for a single structure. Large numbers can be combined to form a power plant.
Photovoltaic cells convert sunlight directly into electricity. When sunlight strikes a PV cell, electrons are dislodged, creating an electrical current. Photovoltaic cells power many of the small calculators and wrist watches in use every day. More complex systems provide electricity to pump water, power communications equipment light homes, and run appliances. Beyond the utility power line, PV is often the lowest-cost means to provide electricity, and almost always simplest and cleanest to operate. The cost of PV has fallen by 90 percent since the early 1970s. Photovoltaics are producing electricity for critical loads from the polar ice caps to the tropics to satellites in outer space. There is a strong market today in developing countries to provide rural electrification with solar panels, which replace kerosene lamps, batteries, and wood fires at a far lower cost than the central station power plants. Photovoltaics are also making inroads as supplementary power for utility customers
