Five years ago, mostly just off-grid types put up wind turbines in their backyards, but today, thanks to new products, big subsidies and sinking costs, the market for grid-tied small wind is exploding.
For many- according to the Pike Research report “Small Wind Power”-, small wind is less expensive than solar panels. While this is limited to certain parts of the country and only those gusty backyards, the industry is definitely taking off.
Backyard wind has begun to creep into the mainstream in just the past few years with the introduction of technology that allow homeowners to connect their turbines to the grid; that is, technology that allows homeowners to feed electricity back into the grid and to use the utilities for backup power.
The first small wind turbine designed specifically for grid-tied residential use was released as recently as 2006 (the Skystream). Since then, backyard wind turbines have hit the market for all types of customers
There are special models for low wind, low noise, for those with only roof access and those who are concerned with aesthetics. Even hardware stores have gotten in on the act and spots like Ace Hardware are offering a model off the shelf while those like Lowes offer backyard turbines on special order.
What to consider before erecting your own turbine
Small wind does seem to be going more mainstream, but for those interested in buying a backyard turbine, there are factors to consider before jumping in.
Despite all the recent hype over backyard wind, experts warn that it shouldn’t be tried by the faint of heart, after all the turbines involve moving parts, which means more maintenance than solar. Those at Home Power Magazine offer a simple litmus test for those considering a device: it’s “probably not for folks who never change the oil in their vehicles (or are willing to spend the bucks to hire someone to do the tower work)”.
While most small turbines have only 2-3 moving parts, according to the American Wind Energy Association (AWEA), “the average residential-sized wind turbine will put on as many “miles” in just four months as the average car does in its 100,000-mile lifetime”.
Assessing your wind regime
Before you even start to compare turbine models, you should check a wind map to see if the wind in your part of the country is even viable for creating sufficient power.
Wind is classed like whitewater, that is on a scale from 1 to 7. While commercial turbines aren’t viable in regions with less than “Class 3” status, small wind turbines are generally cost-effective with at least a Class 2 regime, which is at least 10 to 12.5 miles per hour (4.4 to 5.6 meters per second) at a height of 33 ft (10 meters) above the ground.
This is just a general guideline as specific locations can be affected by terrain; wind can be obstructed by a hill or accelerated by a trough or valley. Also to be considered are the extent of seasonal variations in wind speed, or quantity.
What wind do you have 100 feet up?
Studies in both Massachusetts and the U.K. have shown that many small wind turbines underperform manufacturers’ specifications and that usually is due to lack of information regarding true wind resources at a given site.
“One of the challenges as an installer is that everyone has a windy site,” explained Mark Durrenberger, president of turbine installer New England Breeze, to CNET. “But what you feel on the ground has nothing to do with what you have 100 feet up.”
Watch out for nearby trees
While most turbines come with an 80 to 120 foot tower, the AWEA recommends insuring that the bottom of the turbine’s blades are at least 30 feet above the top of anything within 500 feet. So while additional feet of tower may cost more in up-front costs, it is relatively cheap in the long run. “For instance, installing a 10-kW generator on a 100-foot tower rather than a 60-foot tower involves a 10% increase in overall system cost but can result in 29% more power.”
Any adjacent obstacles to wind, like buildings or trees, can have a considerable effect on turbine performance. Shawn Shaw, an analyst on the Massachusetts study, explained to CNET that a turbine mounted on a 100-foot tower placed next to a 50-foot tree is as effective as a turbine on top of a 50-foot tower.
Though with the right clearance, even poorly rated spots can do well. When we visited the Pickards’ Mountain Eco-Institute in North Carolina, owner Tim Toben explained to us that his turbine outperformed expectations.
“This is a class 1 wind regime so we’re very light wind. And we were told that this would only generate power about 40-50% of the time because of our wind resource, but we’re up on a hilltop and the turbine is about 35 feet about the top of the treelike so we actually get power at 4-5 miles per hour about 80% of the time. And so we’ve been delighted with the output of that wind turbine. So if folks tell you that you can’t do it be sure, put an anemometer up above the treeline and see what you’ve got and you might be pleasantly surprised.”
A few more facts on wind before going shopping
- Be aware of any height restrictions due to local zoning rules.
- If you want your wind turbine to eventually pay for itself, you might want to consider not just your local wind speed, but also your electricity costs. The AEWA gives out this general rule of thumb: “if economics are a concern, a turbine owner should have at least a 10-mph average wind speed and be paying at least 10 cents/kWh for electricity”.
- Payback time: from 6 to 30 years, depending on factors like siting and government incentives.
- If you’re considering a roof-mounted system, you’d better be ready for some vibration. New England installer Durrenberger told CNET he doesn’t recommend them because “it will be like having a sub-woofer in your basement.”
- Watch out for anything that seems too good to be true. Since most popular models of small wind turbines operate at roughly the same efficiency, any “breakthrough technologies” should be regarded with caution.
A selected list of backyard wind turbines
Setup: pole-mounted (Inverter is mounted directly on turbine to reduce efficiency losses. This is only significant if the turbine is located at a distance from your home.)
Cost: $9,000 installed
Output: 2 kW
Setup: roof or pole-mounted; vertical axis turbine
Minimum wind speed: 8 mph
Cost: $7,500 (without installation)
Honeywell Wind Turbine
Distributor: ACE Hardware
Size: 6 feet in diameter, 95 pounds
Setup: Can be mounted on roof (or chimney) or on a pole
Minimum wind: 2 miles per hour, making it 1st among its competitors to generate power from such low speeds.
Wind Terra Eco1200
Manufacturer: Wind Terra
Setup: roof-mounted; vertical axis turbine (blades spin horizontally)
Minimum wind speed: 4-5 mph
Cost: $11,000 installed
Swift Rooftop Energy System
Manufacturer: Cascade Engineering
Size: diameter of 7 feet
Output: 1.5 kW
Type: roof-mounted. Company claims its “outer diffuser” ring (a ring around the blades) cuts the noise level to 35 decibels and reduces vibration.
Price: $10,000-12,000 installed
Manufacturer: Mariah Power
Output: 1.2 kW
Size: 30 feet tall and 2 feet wide, the propeller-less design is bird-safe, relatively quiet — it produces about 25 decibels of noise at five feet, roughly equivalent to the average noise of a residential neighborhood at night
Minimum wind speed: 8 mph (though can survive 100 mph gusts)
Cost: about $4,000 (without installation)
Air-X Wind Generator
Manufacturer: Southwest Windpower
Type: roof-mounted; off-grid only
Output: 400 watts
Minimum wind speed: 7 mph
Manufacturer: Southwest Windpow
Output: 200 watts
Type: off-grid only
Size: 46 inches wide