April 29, 2016

IE Questions: What Size Wind Generator Does An Average House Need?

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An audience member asks: What size wind generator does an average house need?

It’s a great question. Non-utility-scale wind, also known as distributed wind, is on the rise in the U.S. That includes small generators, with a capacity of 100 kilowatts or less. Generators for single homes are usually sized between 5 and 20 kilowatts.


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But unfortunately, it’s not for everyone. If you live in the middle of the city, you likely don’t have much room for a turbine, or access to good wind.

So how can you tell if a home wind generator is right for you?

First, you’ll need space. About an acre of land is the minimum; more is better.

Second, you’ll need to know you have enough wind. The Department of Energy says that small wind installations start to be economical with an average annual wind speed of about 10 miles per hour (4 meters per second).

There are tools you can use to measure wind speed at your home, but there’s no need to take a year’s worth of measurements. The National Renewable Energy Laboratory and the renewable energy consulting firm AWS Truepower have already done the heavy lifting, and developed wind resource maps of the country.

U.S. Annual Average Wind at 30 meters

This one shows annual average wind speeds at 100 feet (30 meters), which is the generally accepted minimum height necessary for a home wind turbine. Look for the light green, orange and red areas – that’s where your chances are best of being a good candidate for a home generator. On the Department of Energy’s website, you can click on a state to see its map in greater detail.

Those estimates aren’t perfect, however. Tall trees can block the breeze – so you’ll need your turbine to be taller than the local foliage.

Third, even with the space and the wind, will a turbine really save you money? That depends on how much you pay for the electricity you use. For a small turbine to pay for itself in a few years, you’ll need to have a monthly electric bill of at least $100-150. Another benchmark is to calculate your electricity cost per kilowatt-hour from your monthly bill. At least 12 cents per kilowatt-hour is a sign a wind turbine might be cost-effective for your home.

Finally, you might need special legal permission to build your generator. Local zoning laws often prohibit structures 100 feet tall. You’ll need to find out how to get special permission from local regulators to build your turbine.

Screen Shot 2016-04-27 at 2.10.20 PMIf you ARE a good candidate, then you are ready to answer our audience question, what size wind turbine does an average house need? And actually, this is the easiest part. Generally, a generator with a capacity of 10 kilowatts is a good bet for a home of 2,000 to 2,500 square feet.

A small wind dealer can help you address all of these requirements in more detail, and can help you decide both if your home is a good candidate for a wind generator, and exactly which size generator is right for you.

One thing the industry experts we talked to emphasized: Make sure you purchase a generator that’s certified by the American Wind Energy Association. Their standard for small wind generators is meant to ensure that your generator will deliver the power it promises.


We received a question via Hearken on this story that we thought warranted an update: What if the wind isn’t blowing?

It’s a great question! Even if you live in a place that has an annual average wind speed of 10 mph, it clearly doesn’t mean that the wind is always blowing hard enough to provide a constant source of electricity for your home.

The wind speed and utility cost estimates we give above are geared more toward systems that ARE connected to the grid. It’s the most common set-up. For these systems, when the wind doesn’t blow, or it’s blowing too little to meet all your electricity need, you draw energy from the utility company, as you normally would. Also, when the wind is blowing MORE strongly than you need, you sell the excess energy back to the grid.

For systems that are NOT connected to the power grid, you would need some form of backup power, like a generator, or a way to store the excess power your generator produces when the wind is blowing. As we’ve reported, battery storage can be a challenge.

More questions about wind, or anything else? Ask us below!