Wind Turbine Payback in Custer County, SD
Wind turbine payback in Custer 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 Custer County, SD averages 5.58 m/s (12.5 mph). A 10 kW turbine there would make about 16,616 kWh a year, worth $2,423 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 41 years, and the turbine is built to last about 20.
What to do in Custer County
A home turbine is not worth buying for savings in Custer County unless your spot is far windier than the county average, 8.1 m/s at the hub against 5.58 m/s here. Per kW, solar panels would make about 1,282 kWh a year here against the turbine's 1,662, so get a solar quote first.
What would have to change
- Power would have to cost 30¢/kWh, 2.1 times what SD pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 5.58. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Custer County is the 1,176th 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 Custer County
January is the strongest month here, at 6.33 m/s and about 1,883 kWh. July is the weakest, 4.73 m/s and 916 kWh, so the best month makes 2.1 times the worst. November to March brings in 50% of the year's output in Custer County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.33 m/s | 1,883 kWh | $275 |
| February | 5.89 m/s | 1,449 kWh | $211 |
| March | 5.77 m/s | 1,531 kWh | $223 |
| April | 5.78 m/s | 1,487 kWh | $217 |
| May | 5.49 m/s | 1,356 kWh | $198 |
| June | 5.12 m/s | 1,095 kWh | $160 |
| July | 4.73 m/s | 916 kWh | $134 |
| August | 4.81 m/s | 955 kWh | $139 |
| September | 5.14 m/s | 1,110 kWh | $162 |
| October | 5.72 m/s | 1,498 kWh | $218 |
| November | 5.95 m/s | 1,590 kWh | $232 |
| December | 6.21 m/s | 1,805 kWh | $263 |
What a taller tower would buy
Measured at 10 m the wind in Custer County averages 4.32 m/s; at 50 m it is 6.28 m/s. That gives a shear exponent of 0.232, typical of ordinary open country. Going from 20 m to 50 m takes output from 13,060 to 21,781 kWh a year, 67% 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 | 5.08 m/s | 13,060 kWh | 53 years |
| 30 m | 5.58 m/s | 16,603 kWh | 41 years |
| 40 m | 5.96 m/s | 19,431 kWh | 35 years |
| 50 m | 6.28 m/s | 21,781 kWh | 32 years |
Counties around Custer County
4 of the 6 closest counties are windier at turbine height; the windiest, Niobrara County, averages 6.56 m/s.
- Fall River County, SD: 6.21 m/s, 21,262 kWh, payback 32 years (32 mi)
- Pennington County, SD: 5.76 m/s, 17,932 kWh, payback 38 years (39 mi)
- Lawrence County, SD: 5.27 m/s, 14,397 kWh, payback 48 years (49 mi)
- Oglala Lakota County, SD: 5.99 m/s, 19,630 kWh, payback 35 years (51 mi)
- Weston County, WY: 5.46 m/s, 15,749 kWh, payback 45 years (56 mi)
- Niobrara County, WY: 6.56 m/s, 23,849 kWh, payback 30 years (66 mi)
Sun versus wind in Custer County
Custer County gets 4.39 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,282 kWh a year; one kW of the turbine above makes 1,662. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.3 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.