How Do Photovoltaic Systems Work?

Photovoltaic is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property called the photoelectric effect that can cause them to absorb photons of light and release electrons. When these free electrons are caught, an electrical current is resulted that can be used as electricity.

The photoelectric effect was first noted by a French physicist, Edmund Bequerel, in 1839, who revealed that certain materials would produce small quantities of electric current when exposed to light. In 1905, Albert Einstein described the character of light and the photoelectric effect on which photovoltaic technology is based, for which he later won a Nobel prize in physics. The 1st photovoltaic module was built by Bell Labs in 1954. It was promoted as a solar battery and was mostly just a curiosity as it was too expensive to gain widespread use.

In the 1960s, the space industry started to make the first significant usage of the technology to provide power on board spaceship. Through the space programs, the technology advanced, its trustworthiness was established, and the price started to decline. During the energy crisis in the 1970s, photovoltaic technology gained recognition as a source of power for non-space applications.

Solar cells are made from the same kinds of semiconductor materials,eg silicon, employed in the microelectronics industry. For photovoltaic power cells, a thin semiconductor wafer is specifically treated to form an electric field, positive on one side and negative on the other. When light energy strikes the solar power cell, electrons are knocked loose from the atoms in the semiconductor material. If electrical conductors are attached to the negative and positive sides, forming an electric circuit, the electrons can be caught in the shape of an electrical current -- that is, electricity. This electricity can then be used to power a load, for example a light or a tool.

A number of solar power cells electrically connected to each other and mounted in a support structure or frame is referred to as a photovoltaic module. Modules are engineered to supply electricity at a certain voltage,eg a standard 12 volts system. The prevailing produced is firmly depending on how much light strikes the module.

Multiple modules can be wired together to form an array. Generally, the bigger area of a module or array, the more electricity it'll be produced. Photovoltaic modules and arrays produce direct-current ( dc ) electricity. They can be connected in both series and parallel electrical arrangements to produce any required voltage and current mix.

Today's most typical PV devices utilize a single junction, or interface, to form an electric field inside a semiconductor such as a PV cell. In a single-junction PV cell, only photons whose energy is the same as or bigger than the band opening of the cell material can free an electron for an electrical circuit. Put simply, the photovoltaic response of single-junction cells is restricted to the part of the suns range whose energy is above the band gap of the soaking up material, and lower-energy photons aren't used.


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