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Solar cells are responsive to light and can convert
light energy into electricity. The photovoltaic
effect can be produced in many kinds of materials,
such as silicon, polycrystalline silicon, amorphous
silicon, gallium arsenide, and copper indium
selenium. Based on the same principle, each is an
example of a crystal light generation process.
P-type crystalline silicon doped with phosphorus
available through N-type silicon forms a P-N
junction.
When solar light irradiates the surface, some
photons are absorbed by the silicon material; photon
energy transfers to silicon atoms so that electronic
transitions take place. A concentration of free
electrons at the PN junction forms on both sides of
the potential difference. When the external circuit
is connected under the action of the voltage, there
will be a current through an external circuit which
generates a certain output power. The essence of
this process: photon energy into electrical energy.
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