Wind Turbine Payback in Carter County, MT
Wind turbine payback in Carter 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 Carter County, MT averages 6.54 m/s (14.6 mph). A 10 kW turbine there would make about 23,702 kWh a year, worth $3,349 at MT's 14.13¢/kWh. Against an installed cost of about $100,000, that is a payback of 30 years, and the turbine is built to last about 20.
What to do in Carter County
A home turbine is not worth buying for savings in Carter County unless your spot is far windier than the county average, 8.2 m/s at the hub against 6.54 m/s here. Per kW, solar panels would make about 1,235 kWh a year here against the turbine's 2,370, so get a solar quote first.
What would have to change
- Power would have to cost 21¢/kWh, 1.5 times what MT pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 6.54. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MT
Carter County is the 158th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in MT is Fallon County at 6.64 m/s, payback 29 years.
Month by month in Carter County
January is the strongest month here, at 7.31 m/s and about 2,485 kWh. July is the weakest, 5.59 m/s and 1,415 kWh, so the best month makes 1.8 times the worst. November to March brings in 47% of the year's output in Carter County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.31 m/s | 2,485 kWh | $351 |
| February | 6.70 m/s | 1,910 kWh | $270 |
| March | 6.78 m/s | 2,164 kWh | $306 |
| April | 6.65 m/s | 2,014 kWh | $285 |
| May | 6.43 m/s | 1,946 kWh | $275 |
| June | 6.06 m/s | 1,658 kWh | $234 |
| July | 5.59 m/s | 1,415 kWh | $200 |
| August | 5.73 m/s | 1,505 kWh | $213 |
| September | 6.23 m/s | 1,757 kWh | $248 |
| October | 6.94 m/s | 2,258 kWh | $319 |
| November | 6.98 m/s | 2,212 kWh | $313 |
| December | 7.09 m/s | 2,351 kWh | $332 |
What a taller tower would buy
Measured at 10 m the wind in Carter County averages 5.21 m/s; at 50 m it is 7.27 m/s. That gives a shear exponent of 0.207, typical of ordinary open country. Going from 20 m to 50 m takes output from 19,808 to 28,951 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 | 6.01 m/s | 19,808 kWh | 36 years |
| 30 m | 6.54 m/s | 23,705 kWh | 30 years |
| 40 m | 6.94 m/s | 26,626 kWh | 27 years |
| 50 m | 7.27 m/s | 28,951 kWh | 24 years |
Counties around Carter County
3 of the 6 closest counties are windier at turbine height; the windiest, Bowman County, averages 6.79 m/s.
- Harding County, SD: 6.62 m/s, 24,289 kWh, payback 28 years (51 mi)
- Powder River County, MT: 6.12 m/s, 20,594 kWh, payback 34 years (51 mi)
- Fallon County, MT: 6.64 m/s, 24,436 kWh, payback 29 years (56 mi)
- Bowman County, ND: 6.79 m/s, 25,529 kWh, payback 31 years (64 mi)
- Crook County, WY: 5.61 m/s, 16,834 kWh, payback 42 years (64 mi)
- Butte County, SD: 6.15 m/s, 20,816 kWh, payback 33 years (65 mi)
Sun versus wind in Carter County
Carter 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 2,370. 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.