Wind Turbine Payback in Clayton County, IA
Wind turbine payback in Clayton 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 Clayton County, IA averages 6.07 m/s (13.6 mph). A 10 kW turbine there would make about 20,223 kWh a year, worth $2,942 at IA's 14.55¢/kWh. Against an installed cost of about $100,000, that is a payback of 34 years, and the turbine is built to last about 20.
What to do in Clayton County
A home turbine is not worth buying for savings in Clayton County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.07 m/s here. Per kW, solar panels would make about 1,156 kWh a year here against the turbine's 2,022, so get a solar quote first.
What would have to change
- Power would have to cost 25¢/kWh, 1.7 times what IA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.07. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IA
Clayton County is the 717th 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 Clayton County
April is the strongest month here, at 6.89 m/s and about 2,159 kWh. August is the weakest, 4.82 m/s and 964 kWh, so the best month makes 2.2 times the worst. November to March brings in 48% of the year's output in Clayton County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.58 m/s | 2,038 kWh | $297 |
| February | 6.67 m/s | 1,891 kWh | $275 |
| March | 6.59 m/s | 2,043 kWh | $297 |
| April | 6.89 m/s | 2,159 kWh | $314 |
| May | 6.17 m/s | 1,780 kWh | $259 |
| June | 5.47 m/s | 1,302 kWh | $189 |
| July | 4.86 m/s | 984 kWh | $143 |
| August | 4.82 m/s | 964 kWh | $140 |
| September | 5.75 m/s | 1,468 kWh | $214 |
| October | 6.38 m/s | 1,915 kWh | $279 |
| November | 6.46 m/s | 1,902 kWh | $277 |
| December | 6.26 m/s | 1,836 kWh | $267 |
What a taller tower would buy
Measured at 10 m the wind in Clayton County averages 4.76 m/s; at 50 m it is 6.8 m/s. That gives a shear exponent of 0.222, typical of ordinary open country. Going from 20 m to 50 m takes output from 16,387 to 25,602 kWh a year, 56% 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 | 5.55 m/s | 16,387 kWh | 42 years |
| 30 m | 6.07 m/s | 20,230 kWh | 34 years |
| 40 m | 6.47 m/s | 23,196 kWh | 30 years |
| 50 m | 6.8 m/s | 25,602 kWh | 27 years |
Counties around Clayton County
2 of the 6 closest counties are windier at turbine height; the windiest, Fayette County, averages 6.18 m/s.
- Delaware County, IA: 6.06 m/s, 20,149 kWh, payback 34 years (26 mi)
- Fayette County, IA: 6.18 m/s, 21,039 kWh, payback 33 years (26 mi)
- Allamakee County, IA: 6.09 m/s, 20,371 kWh, payback 34 years (30 mi)
- Grant County, WI: 6 m/s, 19,704 kWh, payback 27 years (32 mi)
- Crawford County, WI: 6 m/s, 19,704 kWh, payback 27 years (34 mi)
- Dubuque County, IA: 5.97 m/s, 19,482 kWh, payback 35 years (35 mi)
Sun versus wind in Clayton County
Clayton County gets 3.96 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,156 kWh a year; one kW of the turbine above makes 2,022. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.7 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.