The power that comes from that
plug in the wall is known as AC. This stands for alternating current and
is sinusoidal in nature (it goes up and down really fast). The power that
your solar cells will generate is DC, direct current (one flat level). The
power goes from the solar cells into the batteries, still DC, to the
inverter. The inverter converts the power into a usable AC waveform. On
the downside inverters aren’t perfectly efficient (85% is average) so you
will experience some losses. The alternate is to purchase DC appliances
which are sold through specialty sources. You won’t need to convert your
power to use these but they are more expensive.
A bit about electricity and
safety: Electricity will kill you if you are not careful. The most
dangerous form of electricity is the AC current that comes out of your
sockets. It oscillates at a rate that is low enough that your heart
tries to match it, fibrillation, and your muscles lock onto it so you
can’t escape. DC isn’t as dangerous but can still inflict painful
burns and even kill you. Always treat it with utmost respect.
If you don’t understand what you are doing find a qualified expert to do
it for you.
One of the most important aspects
of a solar system is exposure to the sun. Unless you live in a
desert you will need to worry about placement. In general, homes in
the U.S. should place the solar cells directly south at an angle
equal to the latitude. Also be sure to place the cells in an area
where no shade will spill on them during the day, this can significantly
reduce the amount of power it produces. Unless diodes are used
between cells, then not a worry, but these are more expensive from the
factory.
If you live in northern Minnesota,
PV may not be your best choice. The Department of Energy produces a
wind map which will show you if you live in an area where wind turbine can
work effectively. This map will show two power ratings, one at 10
meters, and the other at 50 meters. Now remember, this is an
average, you may experience higher or lower levels, but if this area
experiences average winds higher then 10 MPH you may have a site that can
generate power cost effectively.
In addition to a turbine you will
need a tower. These guys can be quite pricey and extremely expensive
to install. Some of the small towers are stand alone, most use guy
wires (like on radio towers) to support them. The largest and most
expensive are usually installed professionally, require concrete pads and
a crane or two. So our focus will be on smaller towers that can be
done with the help of several friends. Explore various companies
kits and see how they recommend that it be installed, each system differs
but these folks are very helpful when it comes to questions.
Placement of the turbine and tower
is also very important. They work best in a place where no turbulent
air flow can get to them. Without getting into fluid mechanics we
will go over the basics of turbulence. Place your hand into a sink
with water and bubbles in it. Move your hand quickly from one side
to the other; you can see eddies, surges, and dead zones. Air reacts
in much the same way. If you have a small tower, and it’s not far
from your barn the air flow can be quite turbulent and reduce your
efficiency. One question that you must be pondering is what about
really high winds? Most turbines have protection to keep them going even
if the wind is really blowing hard. Some of the best turbines are
rated to exceed hurricane force winds, but even so, contact your insurance
company and see if your landowners or homeowners insurance will cover any
destructive losses.
The ideal situation calls for a
bit of each. You install both a wind turbine and have a solar system. Some
really great technologies make that possible today, including PV shingles
and roof coverings and stand-alone turbine towers. Other more exotic
technologies are hydropower, Stirling engines, geothermal power, ocean
power and the ever-present quest for fusion. As time goes on, these
technologies will either drop in price or become a reality.
No matter what choice you make,
it will be expensive, and it will take time and effort, but in the end you
will have a self-sufficient system that can supply you and your family’s
needs. So do some searches on the ‘net for companies who sell and install
systems, ask on the various forums, talk to people that have systems on
their homestead and start working towards being self reliant!
Here are two sites/brochures from
the Department of Energy (.PDF format)
http://www.nrel.gov/docs/fy04osti/36680.pdf
http://www.eere.energy.gov/RE/solar.html
