SOUTHWEST WINDPOWER 3-CMLT-1028-02 REV D
SOUTHWEST WINDPOWER Page 8 of 35
Step 1: Site Selection
Site selection is the most important factor affecting the performance of your wind turbine!
The energy in the wind is the kinetic energy of the moving air mass. What a wind turbine does is
convert some of that kinetic energy into mechanical energy, which is then converted to
electricity. The formula for the amount of power in the wind is a cube function of the wind speed.
This means basically that an increase in wind speed of 10% (say from 9 mph to 10 mph) will
result in approximately a 37% increase in the energy available from the wind and a similar
difference in turbine performance. In almost all locations the wind speed increases, as you get
higher off the ground. This is why the taller the tower the better. As a rule, the turbine should be
mounted as high in the air and as far away from obstructions as is possible.
To find the best location to erect your tower and wind turbine, study the area available and take
note of how the prevailing (most common) winds blow through it. If there are trees, buildings,
hills or other obstructions take note of how high they are and where they are in relation to the
prevailing wind direction and your proposed tower location. The best site for your tower and
turbine will be upwind and above any obstructions which may exist. If there are houses or trees
in the surrounding area it is best to mount the turbine at least twice as high as any obstruction in
the area. If the turbine is to be mounted at the crest of a hill or on a beach where winds come
from across the water, a lower tower may be acceptable.
The next consideration in siting your tower and turbine is the distance from the turbine to your
batteries. The shortest distance will require the least amount of wire and reduce the amount of
power lost through the wiring. If a long distance is required between your tower and the
batteries it will be necessary to use heavy gage wire to reduce the resistance of the wire. The
power consumed by the wires can be calculated using the formula:
Power = Current xCurrent x Resistance (P=I2R)
Since the resistance of the wire is directly proportional to its length, making the run shorter will
dramatically reduce the amount of power “lost” in the wires. Refer to the Whisper Owner’s
manual and make sure you are using correct gage wiring to minimize system losses. The
person laying out your power system should be aware of these considerations when the system
is in the planning stages.
Step 2: Mast Pipe and Hardware Selection
Due to the high cost of shipping and the widespread availability of pipe used for the tower,
Southwest Windpower does not provide these materials. Materials are readily available through
most hardware stores or plumbing companies and will cost much less when purchased locally
than if they were shipped from our factory.
The Skystream 3.7® and Whisper 500 is designed to be mounted on a 5” inside diameter pipe
(12.7 cm). The pipe is classified as 5” Schedule 40 steel pipe. Around the world pipe may come
in different sizes. Make sure your pipe is Schedule 40 with a wall thickness of 0.258” (6.5 mm),
and an external diameter of 5.563” (14.1 cm).
NOTE: In some areas there are subsidies and grants available for installing renewable energy
systems. If you live in one of these areas and need an engineering analysis for this tower
