Wind Power for the Home

Wind generators can supplement solar energy systems for big savings.


| June/July 1999



174-12-02

Wind generators in Altamont Pass, California.


COURTESY OF SOUTHWEST WINDPOWER

You're probably aware of the huge wind farms that provide supplemental power to Los Angeles and power entire cities in other countries. I'm excited about the potential for large-scale wind power plants for cities, and in my community I have already begun to see the potential of wind power for the small system do-it-yourselfer.
After apprenticing as an electrician and studying at the Carbondale, Colorado-based Solar Energy International-a nonprofit organization that provides renewable energies education and technical assistance-I started Amazon Power in 1993 and began installing solar in the area. As my clients took an interest in wind, I began installing wind generators to supplement many solar systems.

These generators are often the most sensible way to boost the capacity of an existing photovoltaic (PV) system. A strong wind resource can allow you to have a smaller battery bank for storage. If you're interested in exploring the possibility of adding a small wind turbine to your system, read on for some tips I've gained from working with small units manufactured to provide power to independent homes, small schools and clinics, as well as for pumping water.

Evaluating Wind Potential

First, assess your location for its wind power potential. You can purchase metering devices and obtain average wind speed data from the airport closest to your home. This information is normally collected at 30 feet above ground level, which is about the minimum height to set a wind generator, as wind speeds are somewhat slower and are subject to more obstructions closer to the ground. Inversely, the higher above the ground, the more significant the wind speed.

For a small supplemental generator that can cost as little as $1,000, including the tower and installation, a visual assessment of available wind power can he sufficient. Raise a light flag, and make it a habit to observe trees and shrubbery around your site. If they are perpetually bent, it's a good indication of a persistent wind. At 4 to 7 mph, you can feel the wind on your face and leaves will rustle. At 8 to 12 mph, leaves will be in constant motion and the flag will raise in the wind. Wind speeds of 13 to 18 mph raise dust and move small branches, and at 19 to 24 mph, trees in leaf begin to sway. At 25 mph, large branches begin to move, and you've got great wind-generating potential!

Small generators can be mounted on a pole with guy wires. (I don't recommend mounting a wind generator on your roof, regardless of what some manufacturers might suggest. Even with a small generator, noise from vibration is a problem.) Put the generator on a tilt up pole tower to make it easier to install and maintain This allows you to mount the generator and connect the wires on die ground before raising the tower-no climbing needed! Keep voltage lass down to 2% by using large enough wire. Manufacturers will provide charts to help determine the proper wire size for your installation.

Evaluating Wind Generators

About a year ago, I installed an Air 303, made by Southwest Windpower, for supplemental charging in a 24-volt home/ recording studio system. The system consisted of 12 Solec 50-watt solar modules. 18 Exide 6-volt golf cart batteries, a Trace 4024 sinewave inverter and a Trace C-30 charge controller, with fuses and disconnects for safety. The loads in thus system are a Vestfrost refrigerator/freezer a small water pump, efficient lighting and a recording studio. The PV system could have provided ample power for these loads. but the users were unaccustomed to living with a renewable energy system and neglected to turn off loads when they weren't using them. After a couple of years of operating under a perpetually low- state of charge, the hatter. bank was suffering





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