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Photovoltaic (effect) The "photovoltaic effect" is the basic physical process through which a solar cell converts sunlight into electricity. In 1839, nineteen-year-old Edmund Becquerel, a French experimental physicist, discovered the photovoltaic effect while experimenting with an electrolytic cell made up of two metal electrodes. Becquerel found that certain materials would produce small amounts of electric current when exposed to light. Sunlight is composed of photons, or "packets" of energy.
These photons contain various amounts of energy
corresponding to the different wavelengths of light. When
photons strike a solar cell,
they may be reflected or absorbed, or they may pass right
through. When a photon is absorbed, the energy of the photon
is transferred to an electron in
an atom of the cell (which is
actually a semiconductor).
With its newfound energy, the electron
is able to escape from its normal position associated with
that atom to become part of the current
in an electrical circuit. By
leaving this position, the electron
causes a hole to form. Special
electrical properties of the solar
cell Ña built-in electric field (thanks to a
P-N junction)
Ñprovide the voltage needed to drive the current
through an external load (such as a light bulb).| |
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