Wind Turbine Payback in Harding County, SD
Wind turbine payback in Harding 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 Harding County, SD averages 6.62 m/s (14.8 mph). A 10 kW turbine there would make about 24,289 kWh a year, worth $3,541 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 28 years, and the turbine is built to last about 20.
What to do in Harding County
A home turbine is not worth buying for savings in Harding County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.62 m/s here. Per kW, solar panels would make about 1,229 kWh a year here against the turbine's 2,429, so get a solar quote first.
What would have to change
- Power would have to cost 21¢/kWh, 1.4 times what SD pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.62. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Harding County is the 102nd windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in SD is Todd County at 6.77 m/s, payback 27 years.
Month by month in Harding County
January is the strongest month here, at 7.50 m/s and about 2,594 kWh. July is the weakest, 5.56 m/s and 1,400 kWh, so the best month makes 1.9 times the worst. November to March brings in 48% of the year's output in Harding County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.50 m/s | 2,594 kWh | $378 |
| February | 6.81 m/s | 1,968 kWh | $287 |
| March | 6.86 m/s | 2,212 kWh | $323 |
| April | 6.73 m/s | 2,060 kWh | $300 |
| May | 6.52 m/s | 1,999 kWh | $291 |
| June | 6.07 m/s | 1,660 kWh | $242 |
| July | 5.56 m/s | 1,400 kWh | $204 |
| August | 5.72 m/s | 1,495 kWh | $218 |
| September | 6.27 m/s | 1,787 kWh | $261 |
| October | 7.03 m/s | 2,316 kWh | $338 |
| November | 7.11 m/s | 2,289 kWh | $334 |
| December | 7.25 m/s | 2,446 kWh | $357 |
What a taller tower would buy
Measured at 10 m the wind in Harding County averages 5.29 m/s; at 50 m it is 7.34 m/s. That gives a shear exponent of 0.203, typical of ordinary open country. Going from 20 m to 50 m takes output from 20,402 to 29,437 kWh a year, 44% 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 | 6.09 m/s | 20,402 kWh | 34 years |
| 30 m | 6.62 m/s | 24,267 kWh | 28 years |
| 40 m | 7.01 m/s | 27,150 kWh | 25 years |
| 50 m | 7.34 m/s | 29,437 kWh | 23 years |
Counties around Harding County
3 of the 6 closest counties are 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 (36 mi)
- Butte County, SD: 6.15 m/s, 20,816 kWh, payback 33 years (48 mi)
- Perkins County, SD: 6.58 m/s, 23,996 kWh, payback 29 years (49 mi)
- Carter County, MT: 6.54 m/s, 23,702 kWh, payback 30 years (51 mi)
- Adams County, ND: 6.73 m/s, 25,093 kWh, payback 32 years (57 mi)
- Slope County, ND: 6.78 m/s, 25,457 kWh, payback 32 years (59 mi)
Sun versus wind in Harding County
Harding County gets 4.21 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,229 kWh a year; one kW of the turbine above makes 2,429. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 2.0 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.