Introduction to Wind
TYPES OF SYSTEMS
Three basic wind energy systems are available. The first is a grid
connected system with battery back up. The second is a grid connected
without battery backup. The third is a stand-alone system that is not
to the grid.
A grid connected wind turbine can reduce your
consumption of utility
power. If the turbine cannot deliver the amount of energy you need the
utility makes up the difference. When the turbine produces more
then your house needs, the excess power can be sold back to the utility
IS YOUR SITE RIGHT FOR WIND
The US Department of Energy (DOE) has regional information that shows
whether wind speeds in your area are generally strong enough to justify
investing in a wind system.
In order for a wind energy system to be effective you
must have at least
10 mile per hour (4.5 meters per second) average wind speeds.
Check out http://www.mrsolar.com/faq/ and read the FAQ titled "What
is the average wind speed for my area?" You will find a wind speed map.
If your site is located in the white areas of this map the regional
average speed is less then 9.8 mph and wind may not be a good choice
If your site has wind speeds greater then 10mph you
have to also consider
the geography of your site. Consider existing structures and future
that my block the wind. Look at trees, buildings, and hills. These
all effect the performance of your wind energy system. Ideally you want
to be the well above any air turbulence caused by obstructions.
If your site is flat this is great. If your site is
hilly you have to
be careful in selecting your location. The best location for a wind
in this case is on top or on the side of a hill that is hit by the
winds. If you are in a gully or on the leeward (sheltered) side of a
you will not receive any wind at all. If you have a complex terrain you
may have to purchase a recording anemometer. This will measure the wind
speeds at you site with the intent of finding the best mounting height
RESEARCH POTENTIAL LEGAL OBSTACLES
Before you invest any time and money, you should research the potential
legal obstacles to installing a wind system. Some jurisdictions, for
restrict the height of structures permitted in residentially zoned
WIND SYSTEM BASICS
All wind systems consist of a wind turbine, a tower, wiring and the
balance of system components: controllers, inverters and/or batteries.
Wind turbines consist of a blades on a rotor, a
generator mounted on
a frame and a tail. The spinning blades turn the rotor capturing the
energy of the wind. This is converted to rotary motion to drive the
The best indication of how much energy a turbine will produce is the
of the rotor. This determines the amount of wind that will intercept
Wind speeds increase with height in flat terrain. This
is why towers
are used to mount the wind turbine. Generally speaking, the higher the
tower the more power the wind system can produce. A general rule of
is to mount the wind turbine 30 feet above any obstacle that is within
300 feet of the tower.
Experiments have shown that relatively small
investments in increased
tower height can yield high rates of return in power production. For
to raise a 10kW generator from a 60 foot tower height to a 100 foot
height involves a 10% increase in overall cost but it can produce 25%
CONNECTING A WIND TURBINE TO THE GRID
There are two ways to tie into the grid, with and without batteries.
If you are looking for a wind system without batteries there is a
selection of equipment to choose from. Bergey Windpower offers a 10kW
turbine with a grid connected inverter that does not require batteries.
If you don't have the proper site for a 10kw generator you are locked
having a system with batteries.
For example, if you want a 400 watt wind turbine from
The turbine is connected directly to the batteries.
This turbine has a charge controller built into it so
it will not over
charge the batteries. Not all turbines have controllers built into
A load diversion controller is typically used to prevent the wind
from damaging the batteries. A load diversion controller is a fancy way
of saying that when the batteries are full a load is turned on to
the extra power from the wind generator. Most times heating elements
used because they can draw a constant high amount of power.
Once your batteries are protected you will need a way
to connect to
the utility grid. A Trace SW inverter is the best way to make this
This inverter runs off of batteries. When the batteries are charged the
inverter acts similar to the load diversion controller. It will take
extra power the wind is producing and will divert or sell this power to
the grid. The SW inverter will also provide you with a way to backup
loads in you home when the utility grid fails. This is a design side
you will still need a controller to prevent the batteries from
This inverter is design to disconnect from the utility grid when the
grid fails. You must have a means to offset the full power output of
wind generator to prevent battery overcharge.
And for example system designs.
American Wind Energy Association
Energy Efficiency and Renewable Energy Network