Wind Turbine Payback in Valley County, MT
Wind turbine payback in Valley 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 Valley County, MT averages 6.11 m/s (13.7 mph). A 10 kW turbine there would make about 20,520 kWh a year, worth $2,899 at MT's 14.13¢/kWh. Against an installed cost of about $100,000, that is a payback of 35 years, and the turbine is built to last about 20.
What to do in Valley County
A home turbine is not worth buying for savings in Valley County unless your spot is far windier than the county average, 8.2 m/s at the hub against 6.11 m/s here. Per kW, solar panels would make about 1,159 kWh a year here against the turbine's 2,052, so get a solar quote first.
What would have to change
- Power would have to cost 24¢/kWh, 1.7 times what MT pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 6.11. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MT
Valley County is the 675th 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 Valley County
October is the strongest month here, at 6.42 m/s and about 1,936 kWh. August is the weakest, 5.57 m/s and 1,403 kWh, so the best month makes 1.4 times the worst. November to March brings in 43% of the year's output in Valley County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.35 m/s | 1,891 kWh | $267 |
| February | 5.85 m/s | 1,429 kWh | $202 |
| March | 6.37 m/s | 1,908 kWh | $270 |
| April | 6.49 m/s | 1,917 kWh | $271 |
| May | 6.29 m/s | 1,858 kWh | $263 |
| June | 5.94 m/s | 1,585 kWh | $224 |
| July | 5.58 m/s | 1,409 kWh | $199 |
| August | 5.57 m/s | 1,403 kWh | $198 |
| September | 5.81 m/s | 1,504 kWh | $213 |
| October | 6.42 m/s | 1,936 kWh | $274 |
| November | 6.43 m/s | 1,879 kWh | $266 |
| December | 6.20 m/s | 1,801 kWh | $254 |
What a taller tower would buy
Measured at 10 m the wind in Valley County averages 4.82 m/s; at 50 m it is 6.83 m/s. That gives a shear exponent of 0.217, typical of ordinary open country. Going from 20 m to 50 m takes output from 16,750 to 25,819 kWh a year, 54% 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 | 5.6 m/s | 16,750 kWh | 42 years |
| 30 m | 6.11 m/s | 20,545 kWh | 34 years |
| 40 m | 6.51 m/s | 23,460 kWh | 30 years |
| 50 m | 6.83 m/s | 25,819 kWh | 27 years |
Counties around Valley County
6 of the 6 closest counties are windier at turbine height; the windiest, Daniels County, averages 6.6 m/s.
- Phillips County, MT: 6.17 m/s, 20,965 kWh, payback 34 years (58 mi)
- Daniels County, MT: 6.6 m/s, 24,142 kWh, payback 29 years (60 mi)
- McCone County, MT: 6.43 m/s, 22,891 kWh, payback 31 years (65 mi)
- Garfield County, MT: 6.41 m/s, 22,743 kWh, payback 31 years (76 mi)
- Roosevelt County, MT: 6.24 m/s, 21,484 kWh, payback 33 years (77 mi)
- Sheridan County, MT: 6.24 m/s, 21,484 kWh, payback 33 years (101 mi)
Sun versus wind in Valley County
Valley County gets 3.97 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,159 kWh a year; one kW of the turbine above makes 2,052. 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.