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Solar Panels
Whether you are ecologically minded or just
hate to keep paying the electricity bill,
solar power may be your answer. Solar panels
converts energy from the sun into hot water or
electricity. Among the reasons for using
solar panels are:
- they are pollution free and maintenance free
(generally 25-40 year life)
- grants/subsidies/rebates from government
and manufacturers reduce the sizeable initial
investment
- you can sell excess electricity to your local
utility
Solar panels are of two kinds:
either
they convert sunlight into electricity
or
they use the warming power of
the sun to
heat water.
Making Electricity
Solar panels with photovoltaic (PV) cells
are used to make electricity. When sunlight
strikes these cells, direct current (DC)
electricity is produced. Consequently, PV's
only create electricity during periods of
sunlight, with the peak amount of electricity
generated midday on a sunny day and declining
with weather and darkness. Converters transform
the current into standard household voltage
(120V AC).
PV systems can be used stand alone, with
batteries, or tied into the local utility
grid (for drawing power and for selling excess
power). Stand alone systems are intended
for remote locations where no utility connection
is available. Batteries enable storing of
electricity for use at darkness or in cloudy
weather; however, battery systems are an
additional expensive. Connection to the local
utility allows you to sell excess power during
the day and to draw on the utility's power
at night and during cloudy weather -- thereby
using the power company as your "battery."
PV systems are an expensive investment and
take up a significant roof area. A panel
generates about 10 watts per square feet
under optimal conditions, so plan according
to the amount of energy you wish to produce
and the sunlight conditions in your area.
Making Hot Water
A different style of solar panels can be
used to create hot water for heating swimming
pools, for domestic use, or for radiant heating.
These units collect heat and transfer it
to water that circulates through them. Inexpensive
systems can be used to meet the demands of
a heated pool. To meet the higher heating
demand of domestic hot water, the panels
are connected in series with a conventional
water heater and work by boosting the incoming
water temperature (sometimes to 100% of target)
in order to reduce the heating requirements
of the conventional water heater. For radiant
heating systems, even larger quantities of
water are required, and so water heated by
the solar panels is feed into storage tanks
for redistribution.
Choosing a the Right Panels
Once you've decided how you are
going to
use solar power, you may find
it helpful
to compare manufacturers' offerings
along
these lines:
- electricity or hot water efficiency per dollar
cost of unit
- if space is a concern, the efficiency per
square foot
- weight of panels
- ease of expandability
- cost of related equipment (transformers,
batteries, grid connections, etc.)
- ease of installation or cost of professional
system design and installation
- warranties
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