How do solar panels work?
v Electricity can be produced directly from solar energy by the photoconversion
mechanism, which exploits the Photovoltaic Effect.
v The photovoltaic effect is the creation of separated positive and negative charges in a
material as a result of the excitation of an electron within the solid from its normal energy
level, to a higher, excited state.
v Photovoltaic cells are made of special materials called semiconductors, so that when light
hits the cell, a certain portion of the light is absorbed into the semiconductor material and
this absorbed energy knocks electrons loose from the semiconductor allowing them to
flow freely.
v The two halves in a photovoltaic cell create an
internal potential energy difference that directs
electrons in one direction, thus creating an electrical
current.
v The potential difference between the two halves of
the cell is created through the process called
doping.
o When the phosphorous is added to pure
silicon, the resulting material is called Ntype (“n” for negative) because of the
prevalence of free electrons.
o When the pure silicon is doped with boron,
the material is called P-type (“p” for
positive) silicon because boron only has
three electrons in its outer shell leaving free
openings to carry the positive charge.