Wind Turbine Payback in Pennington County, SD
Wind turbine payback in Pennington 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 Pennington County, SD averages 5.76 m/s (12.9 mph). A 10 kW turbine there would make about 17,932 kWh a year, worth $2,614 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 38 years, and the turbine is built to last about 20.
What to do in Pennington County
A home turbine is not worth buying for savings in Pennington County unless your spot is far windier than the county average, 8.1 m/s at the hub against 5.76 m/s here. Per kW, solar panels would make about 1,253 kWh a year here against the turbine's 1,793, so get a solar quote first.
What would have to change
- Power would have to cost 28¢/kWh, 1.9 times what SD pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 5.76. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Pennington County is the 1,103rd 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 Pennington County
January is the strongest month here, at 6.45 m/s and about 1,957 kWh. July is the weakest, 4.87 m/s and 990 kWh, so the best month makes 2.0 times the worst. November to March brings in 49% of the year's output in Pennington County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.45 m/s | 1,957 kWh | $285 |
| February | 5.97 m/s | 1,493 kWh | $218 |
| March | 5.99 m/s | 1,669 kWh | $243 |
| April | 5.98 m/s | 1,610 kWh | $235 |
| May | 5.65 m/s | 1,455 kWh | $212 |
| June | 5.15 m/s | 1,114 kWh | $162 |
| July | 4.87 m/s | 990 kWh | $144 |
| August | 4.95 m/s | 1,035 kWh | $151 |
| September | 5.49 m/s | 1,314 kWh | $192 |
| October | 6.06 m/s | 1,713 kWh | $250 |
| November | 6.21 m/s | 1,749 kWh | $255 |
| December | 6.29 m/s | 1,857 kWh | $271 |
What a taller tower would buy
Measured at 10 m the wind in Pennington County averages 4.36 m/s; at 50 m it is 6.55 m/s. That gives a shear exponent of 0.253, typical of ordinary open country. Going from 20 m to 50 m takes output from 13,870 to 23,775 kWh a year, 71% 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 | 5.19 m/s | 13,870 kWh | 50 years |
| 30 m | 5.76 m/s | 17,902 kWh | 38 years |
| 40 m | 6.19 m/s | 21,117 kWh | 33 years |
| 50 m | 6.55 m/s | 23,775 kWh | 29 years |
Counties around Pennington County
4 of the 6 closest counties are windier at turbine height; the windiest, Jackson County, averages 6.49 m/s.
- Custer County, SD: 5.58 m/s, 16,616 kWh, payback 41 years (39 mi)
- Meade County, SD: 6.32 m/s, 22,077 kWh, payback 31 years (42 mi)
- Oglala Lakota County, SD: 5.99 m/s, 19,630 kWh, payback 35 years (48 mi)
- Lawrence County, SD: 5.27 m/s, 14,397 kWh, payback 48 years (54 mi)
- Jackson County, SD: 6.49 m/s, 23,333 kWh, payback 29 years (64 mi)
- Fall River County, SD: 6.21 m/s, 21,262 kWh, payback 32 years (64 mi)
Sun versus wind in Pennington County
Pennington 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 1,793. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.4 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.