PV systems
Power from the sun is a great idea. Cheap and almost continuous (especially
in southern areas) sunlight can be used to provide electricity for everything
from calculators to city blocks.
One key to getting electricity from
sunlight is a device called a photovoltaic cell, or PV cell. PV cells are found
on calculators, sidewalk lighting systems, rooftops, and along highways to power
emergency phones.
PV systems have been around for a long time. It has
been known since 1839 that certain materials can produce electricity when
exposed to sunlight. It wasn't until the 1970s, though, that research spurred by
the space program resulted in commercially viable solar power systems. Their are
multiple materials that can be used in Photovoltaic cells, but today about 99.9%
of them are silicon based. And their structure is as we will see in the more
advanced articles much like that of a semiconductor.
Today, PV cells can be used to provide almost all the electricity needed by
a typical household. They can be installed on rooftops as well as integrated
into windows to provide non-polluting electrical power. No noise no nothing they
quietly produce electricity from the solar rays without you even noticing it.
And they will do so for decades in a row. A solar panel has no moving parts, and
is apart from a cleaning every few years almost maintenance free.
PV
systems can be used to provide all of the power needs of a household, or it can
be integrated with traditional power sources. People living in remote areas that
don't have access to affordable electricity find an alternative with PV systems.
Increasingly, people living in urban areas can use PV systems in conjunction
with regular power grids. If their solar cells generate more electricity than
needed the excess is fed back into the power system reducing their power costs
even more.
There are two types of solar cells available -- standalone
modules or integrated roofing materials. Both are installed on the roof of the
house, but the integrated solar cells have the appearance of regular roofing
shingles.
PV systems cannot be used everywhere. They must be installed
where there is unobstructed sunlight for most of the day. They are most
effective in southern areas which sunshine most of the year. They are very
popular in California, Australia, and Japan. Because of the increase in
efficiency of these systems they are increasingly popular in the more cloud
covered areas of the globe. While energy prices fluctuate solar energy always
has the same price tag $0.
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