Solar
Photovoltaic (PV) Systems
RESIDENTIAL ELECTRICITY
Photovoltaics have been used for many years in the remote home
market. That is, areas where it is too expensive to extend a power
line from the utility electric grid. Homeowners can choose solar
over a loud airpolluting generator, and often solar is the most
cost effective choice. Homeowners who have electric power from
a utility can also have a PV system installed on their home. The
system is less expensive than an off-grid home because it does
not require many of the added components. The homeowner can actually
hook their system up to the utility grid. When their system is
producing more power than they are using, the power is sold to
the utility grid, and their utility meter turns backwards. When
they are using more power than their system is producing, they
buy power from the grid, and the utility meter turns forward.
At the end of the month or year (depending upon what they set
up with the utility) the net amount is analyzed. Overall, if they
used the same amount of energy they produced, they do not owe
the utility any money, if they used slightly more than produced,
they owe the utility for that small amount of power, and if they
produced more than they used, the utility owes them a certain
rate for that power.
For many years, PV systems have also been used for a varieties
of other uses, for instance:
LIGHTING
PV is being used to power thousands of traditional lighting application
around the world. It is also being used to meet many specialized
needs such as warning lights for street crossing, bus stops, highways
and waterways, airports and heliports and emergency call boxes
on the freeways.
WATER PUMPING
Supplying sufficient clean, safe water is a major concern of nearly
every country in the world. Nearly 2 billion people in rural areas
of the developing world do not have access to safe sources of
water. The United Nations estimates that it would cost more than
$90 billion to meet the world's needs for clean water alone. Worldwide,
there are more than 20,000 solarpowered systems in use to pump
water for human consumption and agricultural uses, including watering
livestock and crop irrigation. Because water consumption increases
as sunlight increases, photovoltaic technology is often an ideal
power generating source.
RURAL ELECTRIFICATION
Rural electrification programs in many countries have met with
varying degrees of success, but other countries have no such program.
About 75% of the world's population are still without access to
electricity. One option to the high cost of developing electric
power plants is to install PV systems. The advantages of PV are
modularity, ease of operation, reliability, and no fuel requirements,
making them very desirable for rural electrification projects.
For example in French Polynesia, 30,000 - 40,000 people live on
the outer islands, separated by hundreds of miles of rugged terrain.
Centralized generation is impossible, fuel delivery and servicing
make diesel generation impractical. Since 1981, the South Pacific
Institute for Renewable Energy has electrified nearly 2500 homes
on 23 different island using individual PV systems.
DISASTER PREVENTION & PREPAREDNESS
PV power can help prevent or wam of pending disasters. Products
such as PV powered warning lights, have been instrumental in avoiding
accidents in the home, workplace, and in all transportation sectors.
Other PV systems power forecast monitoring devices and weather
tracking systems. When disaster does strike, power supplies are
usually disrupted or destroyed for a time. The ability to quickly
supply power for water pumps communications, hospital and other
emergency relief efforts, is paramount. PV systems are particularly
well suited to these operations because they are reliable and
can be installed quickly. Many PV systems were used to provide
power after Hurricane Hugo and the Northridge earthquake.
