Wind Turbine Payback in Grant County, WI
Wind turbine payback in Grant 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 Grant County, WI averages 6 m/s (13.4 mph). A 10 kW turbine there would make about 19,704 kWh a year, worth $3,754 at WI's 19.05¢/kWh. Against an installed cost of about $100,000, that is a payback of 27 years, and the turbine is built to last about 20.
What to do in Grant County
A home turbine is not worth buying for savings in Grant County unless your spot is far windier than the county average, 6.9 m/s at the hub against 6 m/s here. Per kW, solar panels would make about 1,148 kWh a year here against the turbine's 1,970, so get a solar quote first.
What would have to change
- Power would have to cost 25¢/kWh, 1.3 times what WI pays now.
- Or the average wind at the hub would have to be 6.9 m/s instead of 6. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of WI
Grant County is the 840th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in WI is Manitowoc County at 7.32 m/s, payback 18 years.
Month by month in Grant County
April is the strongest month here, at 6.81 m/s and about 2,109 kWh. August is the weakest, 4.76 m/s and 928 kWh, so the best month makes 2.3 times the worst. November to March brings in 48% of the year's output in Grant County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.49 m/s | 1,980 kWh | $377 |
| February | 6.62 m/s | 1,864 kWh | $355 |
| March | 6.50 m/s | 1,986 kWh | $378 |
| April | 6.81 m/s | 2,109 kWh | $402 |
| May | 6.07 m/s | 1,716 kWh | $327 |
| June | 5.41 m/s | 1,264 kWh | $241 |
| July | 4.83 m/s | 967 kWh | $184 |
| August | 4.76 m/s | 928 kWh | $177 |
| September | 5.67 m/s | 1,417 kWh | $270 |
| October | 6.32 m/s | 1,874 kWh | $357 |
| November | 6.38 m/s | 1,851 kWh | $353 |
| December | 6.18 m/s | 1,789 kWh | $341 |
What a taller tower would buy
Measured at 10 m the wind in Grant County averages 4.69 m/s; at 50 m it is 6.72 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 15,879 to 25,020 kWh a year, 58% 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 | 5.48 m/s | 15,879 kWh | 33 years |
| 30 m | 6 m/s | 19,678 kWh | 27 years |
| 40 m | 6.39 m/s | 22,623 kWh | 23 years |
| 50 m | 6.72 m/s | 25,020 kWh | 21 years |
Counties around Grant County
3 of the 6 closest counties are windier at turbine height; the windiest, Richland County, averages 6.09 m/s.
- Crawford County, WI: 6 m/s, 19,704 kWh, payback 27 years (28 mi)
- Dubuque County, IA: 5.97 m/s, 19,482 kWh, payback 35 years (30 mi)
- Iowa County, WI: 6.01 m/s, 19,778 kWh, payback 27 years (30 mi)
- Clayton County, IA: 6.07 m/s, 20,223 kWh, payback 34 years (32 mi)
- Lafayette County, WI: 5.96 m/s, 19,408 kWh, payback 27 years (32 mi)
- Richland County, WI: 6.09 m/s, 20,371 kWh, payback 26 years (37 mi)
Sun versus wind in Grant County
Grant County gets 3.93 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,148 kWh a year; one kW of the turbine above makes 1,970. 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.