Wind Turbine Payback in Walworth County, SD
Wind turbine payback in Walworth 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 Walworth County, SD averages 6.51 m/s (14.6 mph). A 10 kW turbine there would make about 23,481 kWh a year, worth $3,423 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 Walworth County
A home turbine is not worth buying for savings in Walworth County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.51 m/s here. Per kW, solar panels would make about 1,206 kWh a year here against the turbine's 2,348, so get a solar quote first.
What would have to change
- Power would have to cost 21¢/kWh, 1.5 times what SD pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.51. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Walworth County is the 193rd 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 Walworth County
October is the strongest month here, at 7.02 m/s and about 2,308 kWh. July is the weakest, 5.79 m/s and 1,544 kWh, so the best month makes 1.5 times the worst. November to March brings in 42% of the year's output in Walworth County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.54 m/s | 2,014 kWh | $294 |
| February | 6.28 m/s | 1,671 kWh | $244 |
| March | 6.74 m/s | 2,137 kWh | $312 |
| April | 7.01 m/s | 2,229 kWh | $325 |
| May | 6.80 m/s | 2,176 kWh | $317 |
| June | 6.27 m/s | 1,785 kWh | $260 |
| July | 5.79 m/s | 1,544 kWh | $225 |
| August | 5.85 m/s | 1,578 kWh | $230 |
| September | 6.65 m/s | 2,014 kWh | $294 |
| October | 7.02 m/s | 2,308 kWh | $337 |
| November | 6.64 m/s | 2,009 kWh | $293 |
| December | 6.48 m/s | 1,975 kWh | $288 |
What a taller tower would buy
Measured at 10 m the wind in Walworth County averages 5.2 m/s; at 50 m it is 7.22 m/s. That gives a shear exponent of 0.204, typical of ordinary open country. Going from 20 m to 50 m takes output from 19,623 to 28,601 kWh a year, 46% 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 | 5.99 m/s | 19,623 kWh | 35 years |
| 30 m | 6.51 m/s | 23,447 kWh | 29 years |
| 40 m | 6.9 m/s | 26,316 kWh | 26 years |
| 50 m | 7.22 m/s | 28,601 kWh | 24 years |
Counties around Walworth County
2 of the 6 closest counties are windier at turbine height; the windiest, McPherson County, averages 6.65 m/s.
- Campbell County, SD: 6.57 m/s, 23,922 kWh, payback 29 years (25 mi)
- Potter County, SD: 6.43 m/s, 22,891 kWh, payback 30 years (26 mi)
- Edmunds County, SD: 6.46 m/s, 23,112 kWh, payback 30 years (40 mi)
- Dewey County, SD: 6.39 m/s, 22,595 kWh, payback 30 years (44 mi)
- McPherson County, SD: 6.65 m/s, 24,509 kWh, payback 28 years (47 mi)
- Sully County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (49 mi)
Sun versus wind in Walworth County
Walworth County gets 4.13 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,206 kWh a year; one kW of the turbine above makes 2,348. 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.