How Much Power Will a Home Wind Turbine Produce?

By Steve Graham for Networx

A strong wind gust and attractive rebates may not add up to a good deal on residential wind power. Several factors affect the amount of power generated by a home wind turbine. Homeowners should avoid general ratings and carefully study the potential power-generating capacity of a wind turbine on a specific site.

Power Ratings

Most turbines have a power rating in kilowatts (kW). The rating is somewhat like a car’s horsepower figure. It shows which engine or turbine is bigger, but isn’t a direct measure of the machine’s full energy output. The number of “horses under the hood” doesn’t indicate the fuel efficiency or top speed without vehicle weight, driving conditions and other stats. At least most car buyers have already owned a car, so they have a rough idea how to translate horsepower figures. However, homeowners are typically buying their first turbine, so they have nothing for comparison.

Utility bills are measured in kilowatt-hours (kWh) — power usage multiplied by time. For example, a 100-watt light bulb left on for 10 hours uses one kWh. Many companies and industry groups say a 10 kW system will generate about 10,000 kWh per year (equaling the average power usage in a U.S. home), but the real output will be higher or significantly lower. The turbine puts out a maximum of 10 kW under perfect conditions, so it could theoretically generate 10 kW for 24 hours a day 365 days a year, or 87,600 kW per year. With soft breezes, it will generate just a handful of watts.

Calculating the real power output of a wind turbine in watts involves multiplying the mechanical efficiency by the wind speed, air density, and rotor blade length.

Wind Speed

Wind speeds and other weather factors make a bigger difference to power output than a turbine’s parts. This U.S. Department of Energy map shows annual average wind speeds at 50 meters above the ground. Residential wind turbines have been installed in most U.S. states, but many areas do not have enough wind to spin turbines. No matter what the installer or manufacturer says, you won’t generate significant power at speeds below 10 miles per hour.

Above that threshold, energy increases exponentially with speed. A site with 12 mph winds can generate 70 percent more energy than a site with 10 mph winds.

Wind speeds also increase quickly with altitude. A 10 kW turbine generates 30 percent more power on a 100-foot tower than a 60-foot tower. The difference is greater if tall trees or structures block the wind or create turbulence.

Most wind turbines automatically shut down when wind speeds rise above 25 mph to avoid mechanical damage or bodily injuries. A relatively calm area with seasonal windstorms may never generate much wind capacity.

Turbine Size

The other major consideration is the size of the turbine’s rotor blade. Like wind speed, a larger blade will generate exponentially more energy. A 10-foot blade may not look much larger than an 8-foot blade, but the “swept area” is 58 percent larger. That corresponds with a 58-percent increase in energy production per blade rotation.

The other parts of the turbine differ in quality more than output. Look for a reputable company with quality parts and avoid claims of extreme power production.

You might get a good offer on a wind turbine rated at 10 kW, but without considering several mechanical and natural factors, it is hard to determine the actual electric production capacity.

Photo: ell brown on Flickr

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Warren Webber
Warren Webber1 years ago

Live long and prosper!

Lawrence B.
Lawrence B.2 years ago

A propeller dynamic is not a turbine dynamic. You describe Betz Law as a turbine dynamic which professor Betz clearly defined, in physics, as a propeller driven wind mill dynamic. Professes Betz would roll over in his grave at the propagandist re-branding of his propeller dynamic as a turbine dynamic.

Outrageous? Yes it is! Anti-science? Yes it is! Brainwashing? Yes it is!

The multinational “green” wind industry is based on brainwashing and lies. How much torque and at what speed is the real science measurements of machine capabilities. The manufactures will not tell you that, they lie to you to confuse you and you are already brainwashed stupid by the propagandist.

Aristotle pointed out that the only difference between man and animal was innate “common sense” that most people are born with. Aristotle, defined common sense as “Deductive Reasoning”; the foundation of all sciences.

Aristotle also coined and defined “Propaganda” the anti-science and its many forms. Once you are brainwashed to believe a lie and except the lie as truth: you lose your common sense and are under mind control. You are reduced to sub-human, more animal than human; primed to be a debt slave.

Mukesh R.
Mukesh Ramteke4 years ago


Douglas S.
Douglas S.4 years ago


Ruth R.
Ruth R.5 years ago


Trish K.
Trish K.5 years ago

This is year one for the schools first wind turbine. I hope it did well.

Eternal Gardener
Eternal Gardener5 years ago


Carol Smith
Carol Smith5 years ago

I am behind in my emails and trying to catch up. I agree that natural wind does not generate much electricity. However, there are two alternatives to pursue. Use an airfoil effect such as putting a wind turbine in the hood compartment of a car, and leaving the compartment open, or wiring the turbine to a solar array. The array boots the turbine vanes, and the turbine creates more electricity. If the array does not generate enough with one turbine, wire it to boot another turbine and the second turbine will generate more electricity, until we improve both devices more. Another way to get more out of an array is to focus the sunlight on the guts below. Make the glass caps on the housing MAGNIFY light. Or maybe we want to experiment with very weak lasers and possibly refrigeration housing. Get more use out of the light, while keeping temps cool enough that the solar array does not go KERFLOOEY.

Ramona Thompson5 years ago

We need to do something to wean ourselves away from the fossil fuels.

Jailene Santana
Past Member 5 years ago

Good to know.