Wind Turbine Payback in Fall River County, SD
Wind turbine payback in Fall River 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 Fall River County, SD averages 6.21 m/s (13.9 mph). A 10 kW turbine there would make about 21,262 kWh a year, worth $3,100 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 32 years, and the turbine is built to last about 20.
What to do in Fall River County
A home turbine is not worth buying for savings in Fall River County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.21 m/s here. Per kW, solar panels would make about 1,282 kWh a year here against the turbine's 2,126, so get a solar quote first.
What would have to change
- Power would have to cost 24¢/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 6.21. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Fall River County is the 576th 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 Fall River County
January is the strongest month here, at 7.18 m/s and about 2,408 kWh. July is the weakest, 5.19 m/s and 1,174 kWh, so the best month makes 2.1 times the worst. November to March brings in 50% of the year's output in Fall River County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.18 m/s | 2,408 kWh | $351 |
| February | 6.65 m/s | 1,880 kWh | $274 |
| March | 6.44 m/s | 1,954 kWh | $285 |
| April | 6.31 m/s | 1,809 kWh | $264 |
| May | 5.93 m/s | 1,628 kWh | $237 |
| June | 5.60 m/s | 1,377 kWh | $201 |
| July | 5.19 m/s | 1,174 kWh | $171 |
| August | 5.32 m/s | 1,254 kWh | $183 |
| September | 5.71 m/s | 1,446 kWh | $211 |
| October | 6.35 m/s | 1,892 kWh | $276 |
| November | 6.81 m/s | 2,111 kWh | $308 |
| December | 7.07 m/s | 2,339 kWh | $341 |
What a taller tower would buy
Measured at 10 m the wind in Fall River County averages 4.85 m/s; at 50 m it is 6.97 m/s. That gives a shear exponent of 0.225, typical of ordinary open country. Going from 20 m to 50 m takes output from 17,283 to 26,828 kWh a year, 55% 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 | 5.67 m/s | 17,283 kWh | 40 years |
| 30 m | 6.21 m/s | 21,285 kWh | 32 years |
| 40 m | 6.63 m/s | 24,353 kWh | 28 years |
| 50 m | 6.97 m/s | 26,828 kWh | 26 years |
Counties around Fall River County
3 of the 6 closest counties are windier at turbine height; the windiest, Dawes County, averages 6.59 m/s.
- Custer County, SD: 5.58 m/s, 16,616 kWh, payback 41 years (32 mi)
- Dawes County, NE: 6.59 m/s, 24,069 kWh, payback 32 years (40 mi)
- Oglala Lakota County, SD: 5.99 m/s, 19,630 kWh, payback 35 years (48 mi)
- Niobrara County, WY: 6.56 m/s, 23,849 kWh, payback 30 years (49 mi)
- Sioux County, NE: 6.51 m/s, 23,481 kWh, payback 33 years (53 mi)
- Pennington County, SD: 5.76 m/s, 17,932 kWh, payback 38 years (64 mi)
Sun versus wind in Fall River County
Fall River 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 2,126. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.7 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.