Home Wind Turbines

Assessing the quality of wind at a proposed residential wind turbine site doesn't just tell a homeowner if a turbine will generate enough electricity to make the installation cost effective. It can also determine what kind of equipment should be purchased, how it will be installed, and how it will interact with the local power utility. 

Wind turbines need approximately an acre of land to ensure they are placed 250 feet from adjacent structures. In suburbs, this is a matter of consideration for the neighbors, but there is also a mechanical purpose. Adjacent structures, even natural ones like trees, can cause turbulence. Turbines need smooth, even wind flow, which is why they work best when placed on towers that are 85 to 150 feet high. 

Contrary to common perception, wind is not a singular natural phenomenon. A general circulation moves around the earth constantly, but small, regional circulations create their own distinctive patterns as do local winds. Homeowners need a professional wind assessment at the exact location where they are thinking of installing their turbine because the spot will have a unique wind "signature." 

The minimum acceptable level for productive wind is a 10-12 mph annually. Wind tends to blow most in the fall, winter, and spring, dropping off in the summer. Expect daily wind peaks at any locaiton, generally in the afternoon. Although wind assessment "kits" are offered for sale online in a price range of $500 to $5000, the most accurate assessments are conducted by professionals. 

If you're concerned that an assessor working with a wind turbine company is really just a salesman in disguise, get multiple opinions. An assessor will examine regional weather maps and look at quantified, annual climate data. On a "normal" day, one with no forecast severe weather events, the assessor will use an anemomenter to take a ground speed reading at the site. 

The device is outfitted with cups that rotate on a pole to measure wind speed. The telescoping pole will be raised, with readings taken at varying height levels. As a general rule of thumb, the higher the pole is raised, the better the quality of the wind. The progressive readings help to guage the size of the tower required at the site. 

The results of the wind assessment will also determine optimal placement for the turbine, identify sources of turbulence, and rate the overall quality of the wind at the site. If a site is on the low end of acceptable, with winds right at or just under 10 mph, a turbine may still be an option if deep-charge batteries are added to the system to store power for use when the turbine isn't active. 

Most residential systems are grid tied. The home is powered by the turbine when the wind is blowing and draws electricity from the company's grid during periods of calm. Electrical utilities are required to purchase excess power generated by residential turbines through a system called net metering, which allows for the measurement of both energy produced and energy purchased. 

Because residential wind systems have an opening price of $20,000 and can climb as high as $45,000, a professional wind assessment is an absolute requirement before moving forward. It's the only way to get an accurate prediction of what equipment is required, how it will perform, and how much electricity it will produce. Without that information, you run the risk of just wasting your money.