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How Solar Cells Work
Photovoltaic (or PV) systems convert light energy into
electricity. The term "photo" is a stem from
the Greek "phos," which means "light."
"Volt" is named for Alessandro Volta (1745-1827),
a pioneer in the study of electricity.
"Photo-voltaics," then, could literally mean
"light-electricity". Most commonly known as
"solar cells," PV systems are already an important
part of our lives. The simplest systems power many of
the small calculators and wrist watches we use every
day. More complicated systems provide electricity for
pumping water, powering communications equipment, and
even lighting our homes and running our appliances.
In a surprising number of cases, PV power is the cheapest
form of electricity for performing these tasks.
The most important parts of a solar cell are the semiconductor
layers, because this is where the electron current is
created. There are a number of different materials suitable
for making these semiconducting layers, and each has
benefits and drawbacks. Unfortunately, there is no one
ideal material for all types of cells and applications.
In addition to the semiconducting materials, solar cells
consist of a top metallic grid or other electrical contact
to collect electrons from the semiconductor and transfer
them to the external load, and a back contact layer
to complete the electrical circuit. Then, on top of
the complete cell is typically a glass cover or other
type of transparent encapsulant to seal the cell and
keep weather out, and an antireflective coating to keep
the cell from reflecting the light back away from the
cell.
A typical solar cell consists of a cover glass or other
encapsulant, an anti-reflective layer, a front contact
to allow the electrons to enter a circuit and a back
contact to allow them to complete the circuit, and the
semiconductor layers where the electrons begin and complete
their voyages.
Click
here to see
The Department of Energy's presentation on the basics
of photovoltaics.
Please wait briefly for download. If you do not have
the Quicktime plug-in, download it for free
here
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