Chapter 24 Energy Conservation
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for fans, computers, lights, Figure 24-17, and
radios. Bigger PV systems can be used to
operate appliances such as furnace fans, lights,
refrigerators, and security systems.
The portability of PV systems gives them
another advantage and opens new possi-
bilities for their uses. Many smaller portable
devices can run using photovoltaics. There
have been cell phones, calculators, watches,
games, or toys that have been designed to run
on solar power. PV systems can be used to run
devices on boats and recreational vehicles so
that those on board do not have to rely on a
generator during the day.
Photovoltaic locations
Photovoltaics are used in more than a
dozen countries around the world. Since pho-
tovoltaics depend on sunlight, it can be used
just about anywhere on this planet. At the
present time, there are more than 300 PV sys-
tems in the world. Germany has more than
any other country. A useful source for the
most current information can be found on
the Internet at www.pvresources.com. This
site provides a list of the top 300 PV systems
in the world. Updates are provided as new
plants start producing.
Photovoltaic devices are most cost effi cient
in areas where the sun shines most of each
day. This includes places where the weather is
cold. Locations with the most hours of sunlight
provide a higher savings potential. However,
in cloudy conditions, PV systems still function
but at a lower rate.
Incentives and rebates
A majority of the states in the U.S. offer
some type of incentive to residential customers
and businesses that install energy saving
devices, including PV systems. Power compa-
nies are offering these incentives to decrease
the demand on existing power generating
equipment.
To qualify for the incentive, the PV system
must be installed by a contractor that is on the
power company’s list of approved contractors.
After the system is installed, the contractor
tells the power company, and the owner is
issued his or her reward.
Incentives may be a certain amount of
money per watt for PV systems. They could
also be a certain amount per square foot for
solar collectors serving as a source for heating
water. The incentives and rebates for each
state can be found in the Database of State
Incentives for Renewables and Effi ciency on
the website www.dsireusa.org.
Wind Turbines
Wind energy has been used for centuries
to move ships across lakes and oceans. During
the 19th century, windmills were used in the
U.S. to pump water for humans and cattle. It
was during the oil shortages of the late 20th
century that wind energy began to be used
Figure 24-17. The Arizona Senora Desert
Museum outside Tucson operates lights using
photovoltaics.