Wind Turbine Payback in Rock County, MN
Wind turbine payback in Rock 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 Rock County, MN averages 6.46 m/s (14.5 mph). A 10 kW turbine there would make about 23,112 kWh a year, worth $3,800 at MN's 16.44¢/kWh. Against an installed cost of about $100,000, that is a payback of 26 years, and the turbine is built to last about 20.
What to do in Rock County
A home turbine is not worth buying for savings in Rock County unless your spot is far windier than the county average, 7.5 m/s at the hub against 6.46 m/s here. Per kW, solar panels would make about 1,200 kWh a year here against the turbine's 2,311, so get a solar quote first.
What would have to change
- Power would have to cost 22¢/kWh, 1.3 times what MN pays now.
- Or the average wind at the hub would have to be 7.5 m/s instead of 6.46. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MN
Rock County is the 239th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in MN is Lincoln County at 6.68 m/s, payback 25 years.
Month by month in Rock County
April is the strongest month here, at 7.35 m/s and about 2,426 kWh. August is the weakest, 5.44 m/s and 1,326 kWh, so the best month makes 1.8 times the worst. November to March brings in 43% of the year's output in Rock County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.49 m/s | 1,982 kWh | $326 |
| February | 6.58 m/s | 1,841 kWh | $303 |
| March | 6.91 m/s | 2,243 kWh | $369 |
| April | 7.35 m/s | 2,426 kWh | $399 |
| May | 6.80 m/s | 2,171 kWh | $357 |
| June | 6.13 m/s | 1,700 kWh | $279 |
| July | 5.46 m/s | 1,337 kWh | $220 |
| August | 5.44 m/s | 1,326 kWh | $218 |
| September | 6.50 m/s | 1,923 kWh | $316 |
| October | 6.83 m/s | 2,193 kWh | $361 |
| November | 6.70 m/s | 2,042 kWh | $336 |
| December | 6.43 m/s | 1,943 kWh | $319 |
What a taller tower would buy
Measured at 10 m the wind in Rock County averages 5.11 m/s; at 50 m it is 7.21 m/s. That gives a shear exponent of 0.214, typical of ordinary open country. Going from 20 m to 50 m takes output from 19,158 to 28,531 kWh a year, 49% 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 | 5.93 m/s | 19,158 kWh | 32 years |
| 30 m | 6.46 m/s | 23,137 kWh | 26 years |
| 40 m | 6.87 m/s | 26,136 kWh | 23 years |
| 50 m | 7.21 m/s | 28,531 kWh | 21 years |
Counties around Rock County
4 of the 6 closest counties are windier at turbine height; the windiest, Murray County, averages 6.68 m/s.
- Lyon County, IA: 6.46 m/s, 23,112 kWh, payback 30 years (20 mi)
- Pipestone County, MN: 6.65 m/s, 24,509 kWh, payback 25 years (24 mi)
- Nobles County, MN: 6.57 m/s, 23,922 kWh, payback 25 years (25 mi)
- Minnehaha County, SD: 6.46 m/s, 23,112 kWh, payback 30 years (27 mi)
- Moody County, SD: 6.61 m/s, 24,216 kWh, payback 28 years (31 mi)
- Murray County, MN: 6.68 m/s, 24,728 kWh, payback 25 years (35 mi)
Sun versus wind in Rock County
Rock County gets 4.11 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,200 kWh a year; one kW of the turbine above makes 2,311. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.9 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.