Wind Turbine Payback in Slope County, ND
Wind turbine payback in Slope 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 Slope County, ND averages 6.78 m/s (15.2 mph). A 10 kW turbine there would make about 25,457 kWh a year, worth $3,172 at ND's 12.46¢/kWh. Against an installed cost of about $100,000, that is a payback of 32 years, and the turbine is built to last about 20.
What to do in Slope County
A home turbine is not worth buying for savings in Slope County unless your spot is far windier than the county average, 9.1 m/s at the hub against 6.78 m/s here. Per kW, solar panels would make about 1,194 kWh a year here against the turbine's 2,546, so get a solar quote first.
What would have to change
- Power would have to cost 20¢/kWh, 1.6 times what ND pays now.
- Or the average wind at the hub would have to be 9.1 m/s instead of 6.78. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of ND
Slope County is the 34th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in ND is Bowman County at 6.79 m/s, payback 31 years.
Month by month in Slope County
January is the strongest month here, at 7.50 m/s and about 2,592 kWh. July is the weakest, 5.86 m/s and 1,587 kWh, so the best month makes 1.6 times the worst. November to March brings in 46% of the year's output in Slope County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.50 m/s | 2,592 kWh | $323 |
| February | 6.78 m/s | 1,950 kWh | $243 |
| March | 7.03 m/s | 2,314 kWh | $288 |
| April | 6.93 m/s | 2,181 kWh | $272 |
| May | 6.69 m/s | 2,109 kWh | $263 |
| June | 6.29 m/s | 1,795 kWh | $224 |
| July | 5.86 m/s | 1,587 kWh | $198 |
| August | 5.98 m/s | 1,661 kWh | $207 |
| September | 6.56 m/s | 1,959 kWh | $244 |
| October | 7.23 m/s | 2,433 kWh | $303 |
| November | 7.33 m/s | 2,412 kWh | $301 |
| December | 7.29 m/s | 2,471 kWh | $308 |
What a taller tower would buy
Measured at 10 m the wind in Slope County averages 5.45 m/s; at 50 m it is 7.51 m/s. That gives a shear exponent of 0.199, typical of ordinary open country. Going from 20 m to 50 m takes output from 21,619 to 30,604 kWh a year, 42% 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 | 6.26 m/s | 21,619 kWh | 37 years |
| 30 m | 6.78 m/s | 25,487 kWh | 32 years |
| 40 m | 7.18 m/s | 28,347 kWh | 28 years |
| 50 m | 7.51 m/s | 30,604 kWh | 26 years |
Counties around Slope County
1 of the 6 closest counties is windier at turbine height; the windiest, Bowman County, averages 6.79 m/s.
- Bowman County, ND: 6.79 m/s, 25,529 kWh, payback 31 years (23 mi)
- Golden Valley County, ND: 6.68 m/s, 24,728 kWh, payback 33 years (39 mi)
- Billings County, ND: 6.76 m/s, 25,311 kWh, payback 32 years (39 mi)
- Fallon County, MT: 6.64 m/s, 24,436 kWh, payback 29 years (46 mi)
- Stark County, ND: 6.7 m/s, 24,874 kWh, payback 32 years (46 mi)
- Hettinger County, ND: 6.78 m/s, 25,457 kWh, payback 32 years (48 mi)
Sun versus wind in Slope County
Slope County gets 4.09 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,194 kWh a year; one kW of the turbine above makes 2,546. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 2.1 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.