Wind Turbine Payback in Custer County, MT
Wind turbine payback in Custer 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 Custer County, MT averages 6.09 m/s (13.6 mph). A 10 kW turbine there would make about 20,371 kWh a year, worth $2,878 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 Custer County
A home turbine is not worth buying for savings in Custer County unless your spot is far windier than the county average, 8.2 m/s at the hub against 6.09 m/s here. Per kW, solar panels would make about 1,209 kWh a year here against the turbine's 2,037, so get a solar quote first.
What would have to change
- Power would have to cost 25¢/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 6.09. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MT
Custer County is the 701st 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 Custer County
January is the strongest month here, at 6.63 m/s and about 2,071 kWh. July is the weakest, 5.36 m/s and 1,277 kWh, so the best month makes 1.6 times the worst. November to March brings in 46% of the year's output in Custer County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.63 m/s | 2,071 kWh | $293 |
| February | 6.03 m/s | 1,530 kWh | $216 |
| March | 6.24 m/s | 1,824 kWh | $258 |
| April | 6.28 m/s | 1,793 kWh | $253 |
| May | 6.09 m/s | 1,728 kWh | $244 |
| June | 5.78 m/s | 1,487 kWh | $210 |
| July | 5.36 m/s | 1,277 kWh | $180 |
| August | 5.46 m/s | 1,337 kWh | $189 |
| September | 5.80 m/s | 1,498 kWh | $212 |
| October | 6.42 m/s | 1,937 kWh | $274 |
| November | 6.53 m/s | 1,940 kWh | $274 |
| December | 6.45 m/s | 1,959 kWh | $277 |
What a taller tower would buy
Measured at 10 m the wind in Custer County averages 4.81 m/s; at 50 m it is 6.79 m/s. That gives a shear exponent of 0.214, typical of ordinary open country. Going from 20 m to 50 m takes output from 16,623 to 25,529 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 | 5.58 m/s | 16,623 kWh | 43 years |
| 30 m | 6.09 m/s | 20,348 kWh | 35 years |
| 40 m | 6.47 m/s | 23,211 kWh | 31 years |
| 50 m | 6.79 m/s | 25,529 kWh | 28 years |
Counties around Custer County
5 of the 6 closest counties are windier at turbine height; the windiest, Fallon County, averages 6.64 m/s.
- Prairie County, MT: 6.37 m/s, 22,447 kWh, payback 32 years (38 mi)
- Rosebud County, MT: 5.92 m/s, 19,112 kWh, payback 37 years (54 mi)
- Fallon County, MT: 6.64 m/s, 24,436 kWh, payback 29 years (55 mi)
- Powder River County, MT: 6.12 m/s, 20,594 kWh, payback 34 years (59 mi)
- Carter County, MT: 6.54 m/s, 23,702 kWh, payback 30 years (72 mi)
- Dawson County, MT: 6.49 m/s, 23,333 kWh, payback 30 years (76 mi)
Sun versus wind in Custer County
Custer County gets 4.14 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,209 kWh a year; one kW of the turbine above makes 2,037. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.7 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.