Wind Turbine Payback in Lyman County, SD
Wind turbine payback in Lyman 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 Lyman County, SD averages 6.35 m/s (14.2 mph). A 10 kW turbine there would make about 22,299 kWh a year, worth $3,251 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 31 years, and the turbine is built to last about 20.
What to do in Lyman County
A home turbine is not worth buying for savings in Lyman County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.35 m/s here. Per kW, solar panels would make about 1,235 kWh a year here against the turbine's 2,230, so get a solar quote first.
What would have to change
- Power would have to cost 22¢/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 6.35. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Lyman County is the 402nd 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 Lyman County
April is the strongest month here, at 6.85 m/s and about 2,132 kWh. July is the weakest, 5.66 m/s and 1,462 kWh, so the best month makes 1.5 times the worst. November to March brings in 43% of the year's output in Lyman County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.55 m/s | 2,020 kWh | $295 |
| February | 6.23 m/s | 1,641 kWh | $239 |
| March | 6.60 m/s | 2,048 kWh | $299 |
| April | 6.85 m/s | 2,132 kWh | $311 |
| May | 6.55 m/s | 2,020 kWh | $295 |
| June | 6.04 m/s | 1,643 kWh | $240 |
| July | 5.66 m/s | 1,462 kWh | $213 |
| August | 5.76 m/s | 1,524 kWh | $222 |
| September | 6.43 m/s | 1,878 kWh | $274 |
| October | 6.72 m/s | 2,126 kWh | $310 |
| November | 6.48 m/s | 1,911 kWh | $279 |
| December | 6.40 m/s | 1,924 kWh | $281 |
What a taller tower would buy
Measured at 10 m the wind in Lyman County averages 5.03 m/s; at 50 m it is 7.08 m/s. That gives a shear exponent of 0.212, typical of ordinary open country. Going from 20 m to 50 m takes output from 18,447 to 27,613 kWh a year, 50% 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 | 5.83 m/s | 18,447 kWh | 37 years |
| 30 m | 6.35 m/s | 22,324 kWh | 31 years |
| 40 m | 6.75 m/s | 25,260 kWh | 27 years |
| 50 m | 7.08 m/s | 27,613 kWh | 25 years |
Counties around Lyman County
3 of the 6 closest counties are windier at turbine height; the windiest, Tripp County, averages 6.49 m/s.
- Buffalo County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (33 mi)
- Hughes County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (34 mi)
- Tripp County, SD: 6.49 m/s, 23,333 kWh, payback 29 years (38 mi)
- Brule County, SD: 6.45 m/s, 23,038 kWh, payback 30 years (39 mi)
- Jones County, SD: 6.34 m/s, 22,225 kWh, payback 31 years (42 mi)
- Hyde County, SD: 6.4 m/s, 22,669 kWh, payback 30 years (48 mi)
Sun versus wind in Lyman County
Lyman County gets 4.23 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,235 kWh a year; one kW of the turbine above makes 2,230. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.8 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.