How Much Electricity Will a Wind Turbine Produce?

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Once you’ve determined the average wind speed at a site, it is time to determine how much electricity a wind generator could produce at the proposed tower height — and therefore whether it can meet all your needs or what percentage of your needs it will satisfy. This step is fairly easy.

Table 4.1 shows a list of wind turbines and the estimated annual output of each turbine (in kilowatt-hours) at seven different average wind speeds. To see how this table is used, consider an example.



Let’s assume that the average wind speed at a site (at hub height) is 12 miles per hour. Let’s also assume that your load analysis, after efficiency measures have been implemented, indicates you’ll need, on average, 900 kilowatt-hours per month, or 10,800 per year. In the 12 mile-per-hour column, you’ll discover two wind turbines that match your electrical requirements, the WT6000 (by Proven) and BWC (Bergey Wind Power’s) XL-S. If the wind speed at your site is 13 miles per hour, an Endurance wind turbine would meet your needs. The Proven WT 6000 and the Bergey XL-S
would produce more than you need.

Annual energy outputs used to estimate the economic performance of a wind energy system can also be found in an article Mick and Ian published in Home Power magazine (Issue 131), entitled “How to Buy a Wind Generator.”

You can also obtain annual energy output data directly from wind turbine manufacturers. While this data is useful, manufacturers tend to overstate the electric production of their turbines. As a result, we recommend derating their estimated outputs by 20 percent — just to be conservative. (Note that the data from Wisconsin’s Focus on Energy is derated annual energy output; the data in Ian and Mick’s article is manufacturer data and is not derated.)

Once you’ve found the wind turbine that meets your needs, you need to be sure it is the appropriate type of turbine. That is, you need to be sure you select a grid-tied turbine or battery-based turbine, depending on the type of system you are planning on installing.