Wind Turbine Payback in Butler County, IA
Wind turbine payback in Butler County
No. The turbine wears out before it pays for itself.
At 30 m, the height a home turbine tower usually reaches, the wind in Butler County, IA averages 6.17 m/s (13.8 mph). A 10 kW turbine there would make about 20,965 kWh a year, worth $3,050 at IA's 14.55¢/kWh. Against an installed cost of about $100,000, that is a payback of 33 years, and the turbine is built to last about 20.
What to do in Butler County
A home turbine is not worth buying for savings in Butler County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.17 m/s here. Per kW, solar panels would make about 1,174 kWh a year here against the turbine's 2,097, so get a solar quote first.
What would have to change
- Power would have to cost 24¢/kWh, 1.6 times what IA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.17. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IA
Butler County is the 608th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in IA is Dickinson County at 6.59 m/s, payback 29 years.
Month by month in Butler County
April is the strongest month here, at 7.14 m/s and about 2,304 kWh. August is the weakest, 4.85 m/s and 977 kWh, so the best month makes 2.4 times the worst. November to March brings in 47% of the year's output in Butler County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.60 m/s | 2,052 kWh | $299 |
| February | 6.61 m/s | 1,859 kWh | $270 |
| March | 6.76 m/s | 2,152 kWh | $313 |
| April | 7.14 m/s | 2,304 kWh | $335 |
| May | 6.42 m/s | 1,935 kWh | $282 |
| June | 5.60 m/s | 1,380 kWh | $201 |
| July | 4.86 m/s | 987 kWh | $144 |
| August | 4.85 m/s | 977 kWh | $142 |
| September | 5.84 m/s | 1,520 kWh | $221 |
| October | 6.45 m/s | 1,958 kWh | $285 |
| November | 6.62 m/s | 1,997 kWh | $291 |
| December | 6.42 m/s | 1,935 kWh | $282 |
What a taller tower would buy
Measured at 10 m the wind in Butler County averages 4.83 m/s; at 50 m it is 6.92 m/s. That gives a shear exponent of 0.223, typical of ordinary open country. Going from 20 m to 50 m takes output from 17,061 to 26,469 kWh a year, 55% more, before counting the extra cost of the taller tower. Why tower height decides it explains the shear behind these numbers.
| Hub height | Average wind | Output | Payback |
|---|---|---|---|
| 20 m | 5.64 m/s | 17,061 kWh | 40 years |
| 30 m | 6.17 m/s | 21,002 kWh | 33 years |
| 40 m | 6.58 m/s | 24,026 kWh | 29 years |
| 50 m | 6.92 m/s | 26,469 kWh | 26 years |
Counties around Butler County
4 of the 6 closest counties are windier at turbine height; the windiest, Franklin County, averages 6.32 m/s.
- Floyd County, IA: 6.21 m/s, 21,262 kWh, payback 32 years (22 mi)
- Grundy County, IA: 6.17 m/s, 20,965 kWh, payback 33 years (23 mi)
- Bremer County, IA: 6.21 m/s, 21,262 kWh, payback 32 years (23 mi)
- Franklin County, IA: 6.32 m/s, 22,077 kWh, payback 31 years (25 mi)
- Black Hawk County, IA: 6.17 m/s, 20,965 kWh, payback 33 years (30 mi)
- Chickasaw County, IA: 6.21 m/s, 21,262 kWh, payback 32 years (32 mi)
Sun versus wind in Butler County
Butler County gets 4.02 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,174 kWh a year; one kW of the turbine above makes 2,097. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.8 times. Panel output assumes an 80% system performance ratio. Wind or solar runs the same comparison for every county.
How this is worked out
Wind is NASA's Power climate record, the 2001-2025 average at 10 m and 50 m for the county's centre, carried to 30 m with this county's own measured wind shear and spread into hours with a Rayleigh distribution. The turbine is a generic 10 kW, 7 m rotor machine with 10% losses. Cost is $10,000 per kW installed with no tax credit, because the federal one ended in 2025. One county-centre number cannot see your hilltop or your tree line, so treat it as the starting point for a site survey, not a substitute. The full method and its weak spots are in how the numbers are made.