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SOLAR POWER
What's not to love about solar power? It's free, clean,
and available every day. And you don't have to live
in California or the Australian outback to harness the
power of the sun. The costs of solar systems have come
down 80%+ over the past two decades, and as more consumers
take to solar the costs are falling still. There are
a variety of solar power options available, and it's
important to understand the benefits and costs of each
option.
How Solar Power Works
Solar power is produced by using photovoltaic (PV) cells
to capture the energy of the sun and convert it into
electricity. The basic unit of the system is the solar
cell, which are connected together into modules. PV
cells are comprised of semi-conductors, most often made
of silicon (like the chips used in computers). The semiconductors
absorb power when they are struck by light. These modules
or panels of PV cells are what you see installed typically
on the roofs of homes and businesses. The electricity
created by the solar system is DC or direct current,
and the electricity we use in our homes is AC or alternating
currents. Thus solar systems include an inverter which
changes the DC current into useable AC current. Installing
solar systems is a complicated technical process and
most people will benefit by using contractors skilled
in solar technology and electrical installation.
Home Solar Power Systems
There are two main forms of solar systems for residential
use: the “grid-tie” system and the “off-grid”
or stand-alone system. In a grid-tie system, a home
has solar cells but is still connected to the local
power grid. The home solar system includes solar cells
installed on or near a home that collect the sun's energy
and convert it into DC electricity. Then the inverter
converts the DC power into AC power, which can then
be used directly in your home.
Electricity produced by the solar cells that is not
used immediately in the home is returned to the power
grid. When this happens your electricity meter literally
spins backwards as you are passing energy to the grid.
You are also building a credit on your power bill. This
is called “net-metering”. The benefit of
the grid-tied system is that it does not include expensive
batteries to be installed in your home for the storage
of power; the grid acts as the storage system and your
home and the grid exchange power as you need and produce
it.
Off-grid or stand-alone systems are typically used in
remote locations where standard grid-based power is
not available. These systems are more expensive, but
do allow for complete electrical independence. These
systems require deep-cycle batteries for storing the
electricity as well as a charge controller to assure
the flow of electricity from the cells does not over-charge
the batteries.
For a solar system to work well it needs an unobstructed
view of the sun. In the United States, typically the
best orientation for solar panels is to the south as
the sun is in the southern half of the sky (lower in
the winter and higher in the summer).
Solar panels can either be attached directly to a slanting
roof, or bolted onto frames on flat roofs. If your roof
is not a good option, then panels can also be mounted
on the ground. They can either be placed on a fixed
mount frame or on a “tracking mount” that
follows the sun across the sky.
Solar Water Heaters
A solar water heating system is fairly simple. You install
solar panels, typically on your roof, and the sun heats
the panels. Then these solar collectors heat a fluid
in pipes held in the interior of the panel boxes, and
that fluid is transported into the house where it heats
water in a storage tank. The system can include a pump
which circulates the transmission fluid from the roof
to the water tank and back again, but pumpless systems
are also available. In areas where freezing isn't an
issue, systems can heat your water directly. In most
places a type of antifreeze is used and the fluid and
water do not mix.
One convenient and less expensive option if you live
in a warm climate is a solar batch collector. Water
is simply pumped up to a solar storage tank on the roof
and heated by the sun. Then you just use the hot water
as needed. (But you need to make sure you have a roof
that is strong enough to support the weight of the stored
water and the tank.) These units cost less than $1000.
Another great way to save energy and money if you are
a pool-owner is to use solar power to heat your pool.
Solar Power Costs
The cost of a solar system depends on the size of your
home, the orientation of your property, and your electricity
needs. But for a standard medium-size house it can run
from $20,000-$40,000 before rebates.
However, many state and local governments offer incentives
for solar installation that can significantly reduce
the costs. Rebates coupled with federal tax credits
can knock thousands off of your initial investment,
sometimes cutting it in half! Be sure to check with
your local government for these offers.
One way to cut the cost of a solar electric system is
to reduce your electricity use before installing the
system. Such measures as replacing light bulbs with
compact fluorescents and upgrading old appliances can
cut your electricity use (and also your solar investment)
in half. You'll spend a bit of the savings on the new
items, but you'll have that brand new stainless refrigerator
you've been craving too. Low Impact Living's In-Home
Environmental Assessment program will help you understand
what cuts can be made before you go solar and therefore
save you thousands of dollars.
You can also finance solar installation using home equity.
This approach offers the possibility of making you “cash
flow positive” from day one, especially if you
live in an area that has high power prices, good exposure
to the sun, and solid local rebates.
If the cost of a full house solar system is daunting,
a very attractive option can be heating your water with
the power of the sun. A solar water heating system will
save a typical California family $1000 in power costs.
The payback period on these units is typically under
five years.
Other great lower-cost solar options are distributed
solar applications. You can get attractive solar lights
to illuminate your yard or garden. You can also power
a nice fountain or heat your pool using solar energy.
Wind Power
Wind power is clean, plentiful and the world's fastest
growing source of energy. Countries like Germany, Denmark,
Spain and India are becoming major users of wind energy.
While it has been slower to catch on in the U.S., you
can see major wind farms in the American Southwest.
But American farmers and rural residents have known
for a long time that harnessing the power of the wind
makes sense. And if you have the space and vertical
clearance, you can also take advantage of wind power
to lower your emissions and power bills.
How Wind Power Works
Wind turbines capture the wind's kinetic energy to power
a generator that produces electricity. Wind generators
have four main parts: blades (also known as rotors),
a power shaft, gears and a generator. The wind drives
the blades, which turns the shaft, which powers the
generator and electricity is produced.
Installing wind systems is a complicated technical process
and most people will benefit by using contractors skilled
in wind technology and electrical installation.
Home Wind Power Systems
Consumers can purchase wind units for home use. There
are medium-size units that can fulfill all of the electric
needs of a home, or smaller units that can be used as
a supplemental power supply. A wind system typically
lowers a home's electric bill by 50-90% depending on
the size of the system and the wind patterns of the
site.
Wind power systems are most practical in rural areas
or for consumers with an acre or more of land. But check
with your neighbors and local zoning laws – you
may be able to set up a small system in a suburban area.
Depending on the size of your site and your energy consumption
patterns, you’ll likely need a turbine rated in
the 5-15 kilowatt range to make an impact on your energy
needs.
As with solar power, depending on where you live, you
can either use a “grid-tied or a stand-alone system.
In a grid-tie system, a home uses a wind power system
but the house is still connected to the local power
grid. The electricity produced by the wind system that
is not used immediately in the home is returned to the
power grid. When this happens your electricity meter
literally spins backwards as you are passing energy
to the grid. You are also building a credit on your
power bill. This is called “net-metering.? The
benefit of the grid-tied system is that it does not
include expensive batteries to be installed in your
home for the storage of power; the grid acts as the
storage system and your home and the grid exchange power
as you need and produce it.
A stand-alone system requires greater power-generation
capacity and large storage batteries. These systems
are significantly more expensive, but they do give you
total energy independence.
The most important thing to consider is the average
wind speed of your site. In general people living in
coastal areas or in the Great Plains of the U.S. are
the best candidates for wind power. If you want to measure
this yourself, you’ll need a wind-measuring device
called an anemometer. But this takes some serious time
and dedication. Or you can look at the attached map
to estimate the wind power productivity of your location.
Because wind speed increases with altitude, you’ll
want to get your wind generator as high off the ground
as possible. Trees and buildings also interfere with
wind flow so you'll need to keep the wind generator
at least 500 feet away from any of these types of obstructions.
As a rule, a generator mounted on a tower should be
20-30 feet higher than any surrounding trees.
The U.S. Department of Energy has an excellent consumer’s
guide to Small Wind Electric Systems. It will tell you
all you need to know about evaluating your site, determining
the size of the system you'll need, and much more. Be
sure to look at the state-by-state guide to regulations
and incentives for wind power in your state.
Wind Power Costs
The cost of a wind power system depends on how much
power you wish to generate. If you want to supplement
your existing grid-based power, or supplement a solar
system, you can get a small system that will run between
$5,000-10,000. If you want to install a larger system
that will cover most of your power needs, the system
will cost between $20,000-40,000.
Many states offer rebate or tax credit programs to encourage
the uptake of small wind energy systems. Depending on
the size of the system you buy, the amount of power
you use, and any tax or other incentives you may qualify
for, your payback period should be 5-15 years. Like
solar, wind power is a long-term green investment.
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