Calculating the payback period of a wind turbine requires accurate information about the average winds in an area, the lifespan of the turbine, and any additional setup and permit costs. Some wind turbines produce enough power to repay their setup costs within a few years, while other turbines may take decades to earn a profit for their owners. In some cases, a wind turbine has an infinite payback period, as it never returns its setup costs.
An article from the Medill School gives some examples of turbines in the last category. One homeowner set up a $5000 turbine, but because of the small amount of wind power it collects, he does not expect it to earn him $5000 before its expected life span ends.
Another article gives an example of a wind turbine that requires a more dedicated investment. Instead of a small, $5000 turbine that sits on the roof, the homeowner can build a $50,000 turbine that sits on its own tower. NYSERDA estimates that the $50,000 turbine requires another $12,500 in setup costs, and potentially adds $50-$150 per year in maintenance expenses. The maintenance expenses do have some impact on the payback period when it is relatively long. If the wind turbine provides $2500 worth of power each year, $62500/$2450 is 25.5 years, while $62500/2350 is 26.6 years. The extra $100 per year in maintenance adds about a year to the payback period.
Wind collection is much more important. If the homeowner selects a location that offers stronger wind, raising the value of the power the wind turbine provides to $5000 per year, the payback period drops significantly. Maintenance costs become drastically less important. $62500/$3950 is 15.8 years, while $62500/$3850 is 16.2 years, and the higher maintenance expense estimate now only adds about a third of a year to the payback period. According to NYSERDA, a wind speed increase of only 2 mph per hour, from 12 mph to 14 mph, can generate enough additional power to cut the wind turbine payback period by 10 years.
Unfortunately, many locations around the United States do not offer 14 mph winds. Wind Powering America provides a map of the United States that gives detailed information on average wind speeds in every state.
Some states, such as Wyoming and Colorado, include many locations with plentiful wind power, but the West and the Southeast tend to provide lower wind speeds. Many islands also report high average wind speeds. This map reports winds at a height of 80 meters, a typical height for large turbines on wind farms, although a homeowner typically installs a smaller and cheaper 30 meter tall turbine instead. Tower height makes a drastic difference in the amount of wind power a turbine can collect. Compare the Missouri average wind speed maps at 30 and 100 meters.