Is a small wind system right for you? These 10 steps will help you decide.
Determine how much electricity you use and what it costs, annually and by the kilowatt-hour. Then, find ways to make your home more efficient and reduce your energy use. The U.S. Department of Energy (DOE) provides some rules of thumb in its Small Wind Electric Systems: A U.S. Consumer’s Guide
Then, conduct an energy audit of your home to identify ways of using energy more efficiently and ways of reducing energy use. Implementing energy efficiency opportunities will almost always offer a quicker return on your investment and additionally may enhance the viability of a wind turbine project through a lower capital expense associated with a smaller turbine that will satisfy the new lower energy load. This could lower your electricity bill significantly. The National Rural Electric Cooperative Association (NRECA) recently reviewed several Web sites that host online energy audits. The review identified one Web site—Home Energy Saver—as among the best.
Most experts recommend that you have at least one acre of land if you are considering the installation of a small wind system. Smaller parcels may be suitable if adequate tower setbacks can be achieved.
Examine your site for potential turbulence. When wind flows around buildings, trees, and other structures in the landscape, it slows down or becomes turbulent. A wind turbine should be placed in a location where turbulence is minimized. It also should be placed upwind of buildings and trees.
In addition, you should determine the “roughness”—the terrain and density of vegetation on the landscape—within a radius equal to 20 times the tower height, in the prevailing wind direction.
Wind speed varies from year to year, season to season, with the time of day, and with the height above ground. For a grid-connected wind system, an average annual wind speed of 10 mph is usually considered the cutoff. Most experts recommend average annual wind speeds between Class 2 (11.5 mph at hub height) and Class 4 (13.4 mph at hub height). Class 3 sites have average wind speeds of 12.5 mph at hub height. Hub height is the distance from the ground to the center of the turbine rotor.
A small increase in average wind speed results in a large increase in power produced. A site with an average wind speed of 15 mph contains nearly 54% more energy than a site with an average wind speed of 13 mph. The ideal wind resource has relatively stable high speeds. If your trees and vegetation are permanently deformed because of constant wind exposure—known as “flagging”—you may have a good wind resource to generate electricity.
There are several Web sites with wind resource maps. One is the U.S. Department of Energy’s WINDExchange.
You can measure the wind speed at your site using an anemometer on a tower, but this can be expensive. One option is to review data from nearby sites such as airports or state-administered meteorological stations. But airports tend to be sited in sheltered locations, so data on wind speeds may not be a reliable indicator of wind speeds at your site. Computer models are available that can help you estimate your wind resource.
Although the wind at a given site may blow more frequently from the west, more wind energy at that same site may come from different directions. You should find out which directions have the best winds for electricity production to help with micrositing.
You may want to find an installer at this point. Be sure to ask for references, licenses and certifications, proof of insurance, and a performance bond. A good installer can do a site assessment for you.
At this point, you should talk to your cooperative about what you are considering.
Select turbine and calculate tower height based on that output.
An installer also can look at your historic electricity usage and the amount of energy you want a small wind generator to produce. With this information, the installer can help you select a turbine size and tower height.
Most small turbine manufacturers provide an estimated monthly energy output in kilowatt-hours. Experts caution consumers about taking these figures at face value, however. The capital cost recovery analysis worksheet, provided as part of your cooperative’s information packet, will enable you to determine the annual energy output—in kilowatt-hours—of a given small wind system.
Once you know how much electricity you want your wind generator to produce, monthly or annually, you can look at the specifications of all turbines matching that output. Important features to consider include the rotor diameter and the turbine’s revolutions per minute (rpm). Turbines with a lower rpm tend to be quieter and last longer.
The amount of power that a turbine will produce is determined mainly by the diameter of its rotor and its tower height. The diameter defines the rotor’s swept area—the quantity of wind intercepted by the turbine. The larger and higher the swept area (the area through which the rotor blades spin) of the generator’s rotor, the more electricity it can produce. Swept area is the feature that will help you compare the output of one wind generator with another.
Look for turbines with a good track record and a good warranty—five years, if possible. Some experts believe that weight matters; in their view, the heavier the machine, the more robust it is. They say a heavy-duty wind generator is more likely to handle sites with stronger winds or turbulence than a lighter turbine. But lighter weight turbines typically have lower “cut-in” wind speeds and produce more power in lower winds.Tower height. One of the most common installation mistakes is mounting a wind turbine on a tower that is too short. A rule of thumb for tower height is that the wind generator should be at least 30 feet above any trees, buildings, or other structures within 500 feet. Taller towers result in higher wind generation because of reduced ground drag. An additional 40 feet on a tower can substantially increase the power available—by as much as 200%—and return the incremental initial investment with greater energy generation revenues over the lifetime of the turbine. But taller towers also are more expensive.
The question you need to answer is whether the increased tower height is economically justified compared with the increased electricity production. Information on how to answer this question is available on Renew Wisconsin’s website.
Find out what incentives—rebates, buydowns, and loans—are available, and whether you qualify for a U.S. Department of Agriculture (USDA) Section 9006 grant.
The Database of State Incentives for Renewables & Efficiency (DSIRE) provides detailed information on each state’s incentives that apply to renewable energy systems, including small wind. You can access the database at their website.
The Farm Security and Rural Investment Act of 2002, which expired September 30, 2007, included a provision—Section 9006—that provided grants of $2,500 to $500,000 or up to 25% of the eligible costs of rural renewable energy projects. The Farm Bill Extension Act of 2007, which continues agricultural programs through 2012, provides $500 million in grants for small-scale renewable energy projects.
The grants are only available for agricultural producers that earn at least 50% of their income from agricultural products. Small rural businesses also are eligible. But the application process for a grant or loan under Section 9006 can be complicated and time-consuming.
A sample application form is available on DOE’s energy efficiency and renewable energy (EERE) website at http://www.eere.energy.gov/windandhydro/windpoweringamerica/pdfs/farm_bill_small_wind_sample_application.pdf.
A rule of thumb for estimating the cost of a small wind system is $4–10 per installed watt. The total installed cost is the cost of the wind generator and tower plus the cost of permitting, installation, and interconnection to the grid.
The payback for a small wind system is the amount of time it takes for the system to pay for itself in energy savings. You can calculate the payback for a given small wind system by using the capital cost recovery analysis worksheet provided in your cooperative’s information packet for member-consumers.
Determine what zoning regulations, if any, apply to the installation of a wind turbine, and what permits—building, electrical—are required. Talk with your neighbors about your plans.
Zoning regulations vary from state to state, and from one local jurisdiction to the next. Contact your local county officials to learn about zoning laws. These laws may include height restrictions and may require that a wind turbine be set back from your property line. The standard setback for a small wind system is calculated as a distance from the property line equal to the height of the tower. Sometimes, the setback requirement restricts where a tower can be installed.
In many cases, local municipalities do not have any zoning regulations that apply to the installation of wind turbines and towers. As a result, a zoning hearing often becomes part of the processes that an applicant must go through before a building permit is issued.
At zoning hearings, neighbors are allowed to express any concerns they might have about the small wind system. Preparation for these types of meetings is key. The more answers you have ready for questions that are likely to arise, the easier the process will be.
Information on zoning issues is available on the Renew Wisconsin Web site, on the Small Wind Toolbox page. Scroll down to Toolbox—Information for Homeowners and Installers, and look for documents Zoning 1 through Zoning 6.
Contact your local building inspector, board of supervisors, or planning board to learn whether you will need to obtain a building permit. They will provide you with a list of requirements, which will probably include a site plan, a structural analysis on the foundation and tower, and an electrical one-line diagram.
At this stage, talk with neighbors about your plans and listen to any of their concerns. If there are any other small wind turbine owners in your area, talk with them about any concerns their neighbors had and how they dealt with those concerns.
Ask your cooperative about its interconnection requirements, including costs and liability insurance.
If you have not already talked with your cooperative about your plans, do so now. Discuss the steps you have taken to get to this point, and provide information on the small wind system you are considering. You need to make sure that the system meets the cooperative’s criteria for interconnection.
Your cooperative can provide information on its interconnection process and policies as well as a sample interconnection agreement, and answer any questions that you may have. Select “Interconnection Agreement” and submit the form to get more information.
You might want to start looking for an installer by asking any current small wind system owners in your area for references. In addition, contact the manufacturer of the wind turbine you are interested in for recommendations and suggestions for authorized installers.
Another option is to ask your state’s renewable energy organization or energy office. The National Association of State Energy Officials’ website provides contact information for state energy offices. Regional organizations, such as the Midwest Renewable Energy Association (MREA) might also be able to help.
Once you have a short list of installers, contact at least three of them for quotes for the equipment and installation. Question any quote that appears to be too high or too low.
Some questions to ask when considering an installer are:
- Does the company have experience installing grid-connected systems? What models?
- Does the company use licensed and certified contractors? Is the company insured?
- Does the company have any consumer complaints, judgments, or liens against it?
- Will the company help with the applications required by the local building permitting agency and the utility for grid-connected systems?
- How much, if any, of the work will be contracted out?
- When will construction begin and how long will it take?
- What warranty is offered on the installation (covering workmanship for tower and turbine assembly, electrical, and foundation work)? Will the company accept a performance bond?
- Does the company do service and repairs on the equipment?
- Will the company provide references of previous consumers?
Some states link installation requirements to incentives. Vermont, for instance, makes incentives for new small wind systems available only if the system is installed by a participant in the Vermont Solar and Small Wind Partners Program.
Additional information on selecting an installer is available at Renew Wisconsin
Before actually placing an order, ask the manufacturer or installer for the names of consumers who have installed the same make and model. Contact those consumers to ask about machine performance and reliability and support from the manufacturer. Ask if the system is meeting their expectations.
Ensure that the manufacturer offers at least a one-year warranty with an optional extended five-year warranty for all hardware, and that the inverter is Underwriters Laboratories (UL) listed.
If you plan to purchase a rebuilt or remanufactured wind generator, find out the history of the machine, obtain the remanufacturing report the specific turbine that you will be purchasing, be sure there is a warranty, ask about a maintenance contract, and ask about the availability of spare parts.
Additional information is available in the Wind Turbine Buyer’s Guide.
Contract for installation of your small wind system.
This is the final step. If you did not contract for the installation of your wind generator with the manufacturer, contact the installer you found in step 8 and arrange for installation.