How Does a Photovoltaic Solar Cell Work?
Photovoltaic solar cells convert light energy into electricity by absorbing photons of light that knock electrons loose in an electrical circuit. The electrons that were knocked loose and are now looking for an atom to bond to create an electric current within the circuit. Photovoltaic solar cells are usually made with silicon, of which one side has a surplus of electrons and the other side has a scarcity.
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Construction
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A photovoltaic solar cell made up of a semiconductor material that has one positive and one negative side. It has an antireflective coating on the top side of the wafer and non-conductive substrate attached to the bottom side. The semiconductor--an element that gains stability by sharing its electrons with atoms--is usually silicon. One side of the silicon usually is doped with aluminum, gallium or indium to create a scarcity of electrons, and the other side is doped with phosphorous, arsenic or antimony to create a surplus of electrons. Doping means another element's atoms are dispersed within the silicon.
Light Energy to Electricity
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Photons from the light of the sun are absorbed by the photovoltaic cell. For the photovoltaic solar cell to work, the sun's energy needs to be above the band gap of the absorbing material. The band gap is the energy required to knock an electron from the orbit of an atom's nucleus. This free electron can then move about the semiconductor, effectively becoming a mobile electrical charge.
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Moving the Electron
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When the light energy hits the photovoltaic cell, the side with the surplus of electrons releases its extra electron. This electron then becomes a charge that moves through the semiconductor until it finds its way to the side of the semiconductor that has a scarcity of electrons. It will then fill the hole of the atom that's missing electrons. Electrical conductors can be attached to the positive and negative sides of the wafer, forming an electric circuit. The moving electron then travels from one side to the other through these conductors as electrical current.
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