Wind Turbine Payback in Mellette County, SD
Wind turbine payback in Mellette 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 Mellette County, SD averages 6.55 m/s (14.7 mph). A 10 kW turbine there would make about 23,775 kWh a year, worth $3,466 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 29 years, and the turbine is built to last about 20.
What to do in Mellette County
A home turbine is not worth buying for savings in Mellette County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.55 m/s here. Per kW, solar panels would make about 1,253 kWh a year here against the turbine's 2,378, 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 6.55. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Mellette County is the 151st 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 Mellette County
January is the strongest month here, at 7.04 m/s and about 2,323 kWh. July is the weakest, 5.68 m/s and 1,474 kWh, so the best month makes 1.6 times the worst. November to March brings in 45% of the year's output in Mellette County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.04 m/s | 2,323 kWh | $339 |
| February | 6.60 m/s | 1,854 kWh | $270 |
| March | 6.76 m/s | 2,153 kWh | $314 |
| April | 6.96 m/s | 2,200 kWh | $321 |
| May | 6.58 m/s | 2,036 kWh | $297 |
| June | 6.02 m/s | 1,632 kWh | $238 |
| July | 5.68 m/s | 1,474 kWh | $215 |
| August | 5.81 m/s | 1,552 kWh | $226 |
| September | 6.49 m/s | 1,916 kWh | $279 |
| October | 6.89 m/s | 2,230 kWh | $325 |
| November | 6.93 m/s | 2,179 kWh | $318 |
| December | 6.91 m/s | 2,241 kWh | $327 |
What a taller tower would buy
Measured at 10 m the wind in Mellette County averages 5.17 m/s; at 50 m it is 7.31 m/s. That gives a shear exponent of 0.215, typical of ordinary open country. Going from 20 m to 50 m takes output from 19,725 to 29,229 kWh a year, 48% 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 m/s | 19,725 kWh | 35 years |
| 30 m | 6.55 m/s | 23,773 kWh | 29 years |
| 40 m | 6.97 m/s | 26,811 kWh | 26 years |
| 50 m | 7.31 m/s | 29,229 kWh | 24 years |
Counties around Mellette County
2 of the 6 closest counties are windier at turbine height; the windiest, Todd County, averages 6.77 m/s.
- Jones County, SD: 6.34 m/s, 22,225 kWh, payback 31 years (26 mi)
- Todd County, SD: 6.77 m/s, 25,384 kWh, payback 27 years (26 mi)
- Jackson County, SD: 6.49 m/s, 23,333 kWh, payback 29 years (44 mi)
- Tripp County, SD: 6.49 m/s, 23,333 kWh, payback 29 years (47 mi)
- Lyman County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (50 mi)
- Bennett County, SD: 6.73 m/s, 25,093 kWh, payback 27 years (54 mi)
Sun versus wind in Mellette County
Mellette County gets 4.29 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,253 kWh a year; one kW of the turbine above makes 2,378. 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.