Wind Turbine Payback in Stanley County, SD
Wind turbine payback in Stanley 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 Stanley County, SD averages 6.31 m/s (14.1 mph). A 10 kW turbine there would make about 22,003 kWh a year, worth $3,208 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 31 years, and the turbine is built to last about 20.
What to do in Stanley County
A home turbine is not worth buying for savings in Stanley County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.31 m/s here. Per kW, solar panels would make about 1,221 kWh a year here against the turbine's 2,200, so get a solar quote first.
What would have to change
- Power would have to cost 23¢/kWh, 1.6 times what SD pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.31. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Stanley County is the 460th 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 Stanley County
October is the strongest month here, at 6.74 m/s and about 2,136 kWh. July is the weakest, 5.69 m/s and 1,477 kWh, so the best month makes 1.4 times the worst. November to March brings in 42% of the year's output in Stanley County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.44 m/s | 1,951 kWh | $284 |
| February | 6.10 m/s | 1,568 kWh | $229 |
| March | 6.57 m/s | 2,030 kWh | $296 |
| April | 6.81 m/s | 2,110 kWh | $308 |
| May | 6.54 m/s | 2,013 kWh | $293 |
| June | 6.00 m/s | 1,620 kWh | $236 |
| July | 5.69 m/s | 1,477 kWh | $215 |
| August | 5.70 m/s | 1,488 kWh | $217 |
| September | 6.37 m/s | 1,845 kWh | $269 |
| October | 6.74 m/s | 2,136 kWh | $311 |
| November | 6.41 m/s | 1,872 kWh | $273 |
| December | 6.30 m/s | 1,861 kWh | $271 |
What a taller tower would buy
Measured at 10 m the wind in Stanley County averages 5.02 m/s; at 50 m it is 7.01 m/s. That gives a shear exponent of 0.207, typical of ordinary open country. Going from 20 m to 50 m takes output from 18,218 to 27,114 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 | 5.8 m/s | 18,218 kWh | 38 years |
| 30 m | 6.31 m/s | 21,978 kWh | 31 years |
| 40 m | 6.69 m/s | 24,827 kWh | 28 years |
| 50 m | 7.01 m/s | 27,114 kWh | 25 years |
Counties around Stanley County
5 of the 6 closest counties are windier at turbine height; the windiest, Dewey County, averages 6.39 m/s.
- Jones County, SD: 6.34 m/s, 22,225 kWh, payback 31 years (32 mi)
- Sully County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (37 mi)
- Hughes County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (38 mi)
- Haakon County, SD: 6.3 m/s, 21,929 kWh, payback 31 years (40 mi)
- Dewey County, SD: 6.39 m/s, 22,595 kWh, payback 30 years (51 mi)
- Lyman County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (57 mi)
Sun versus wind in Stanley County
Stanley County gets 4.18 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,221 kWh a year; one kW of the turbine above makes 2,200. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.8 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.