Wind Turbine Payback in Brookings County, SD
Wind turbine payback in Brookings 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 Brookings County, SD averages 6.69 m/s (15 mph). A 10 kW turbine there would make about 24,801 kWh a year, worth $3,616 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 Brookings County
A home turbine is not worth buying for savings in Brookings County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.69 m/s here. Per kW, solar panels would make about 1,177 kWh a year here against the turbine's 2,480, so get a solar quote first.
What would have to change
- Power would have to cost 20¢/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 6.69. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Brookings County is the 65th 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 Brookings County
April is the strongest month here, at 7.37 m/s and about 2,439 kWh. July is the weakest, 5.66 m/s and 1,462 kWh, so the best month makes 1.7 times the worst. November to March brings in 44% of the year's output in Brookings County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.81 m/s | 2,178 kWh | $318 |
| February | 6.83 m/s | 1,983 kWh | $289 |
| March | 7.00 m/s | 2,300 kWh | $335 |
| April | 7.37 m/s | 2,439 kWh | $356 |
| May | 6.96 m/s | 2,272 kWh | $331 |
| June | 6.30 m/s | 1,803 kWh | $263 |
| July | 5.66 m/s | 1,462 kWh | $213 |
| August | 5.69 m/s | 1,478 kWh | $215 |
| September | 6.80 m/s | 2,103 kWh | $307 |
| October | 7.13 m/s | 2,376 kWh | $346 |
| November | 6.98 m/s | 2,210 kWh | $322 |
| December | 6.73 m/s | 2,134 kWh | $311 |
What a taller tower would buy
Measured at 10 m the wind in Brookings County averages 5.35 m/s; at 50 m it is 7.42 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 20,895 to 29,989 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 | 6.16 m/s | 20,895 kWh | 33 years |
| 30 m | 6.69 m/s | 24,795 kWh | 28 years |
| 40 m | 7.09 m/s | 27,694 kWh | 25 years |
| 50 m | 7.42 m/s | 29,989 kWh | 23 years |
Counties around Brookings County
1 of the 6 closest counties is windier at turbine height; the windiest, Deuel County, averages 6.71 m/s.
- Moody County, SD: 6.61 m/s, 24,216 kWh, payback 28 years (26 mi)
- Lincoln County, MN: 6.68 m/s, 24,728 kWh, payback 25 years (26 mi)
- Deuel County, SD: 6.71 m/s, 24,947 kWh, payback 28 years (27 mi)
- Hamlin County, SD: 6.69 m/s, 24,801 kWh, payback 28 years (28 mi)
- Lake County, SD: 6.61 m/s, 24,216 kWh, payback 28 years (29 mi)
- Kingsbury County, SD: 6.57 m/s, 23,922 kWh, payback 29 years (35 mi)
Sun versus wind in Brookings County
Brookings County gets 4.03 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,177 kWh a year; one kW of the turbine above makes 2,480. 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.