Wind Turbine Payback in Darke County, OH
Wind turbine payback in Darke 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 Darke County, OH averages 5.77 m/s (12.9 mph). A 10 kW turbine there would make about 18,006 kWh a year, worth $3,387 at OH's 18.81¢/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 Darke County
A home turbine is not worth buying for savings in Darke County unless your spot is far windier than the county average, 6.9 m/s at the hub against 5.77 m/s here. Per kW, solar panels would make about 1,150 kWh a year here against the turbine's 1,801, so get a solar quote first.
What would have to change
- Power would have to cost 28¢/kWh, 1.5 times what OH pays now.
- Or the average wind at the hub would have to be 6.9 m/s instead of 5.77. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of OH
Darke County is the 1,088th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in OH is Lake County at 6.53 m/s, payback 23 years.
Month by month in Darke County
January is the strongest month here, at 6.68 m/s and about 2,101 kWh. August is the weakest, 4.29 m/s and 692 kWh, so the best month makes 3.0 times the worst. November to March brings in 53% of the year's output in Darke County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.68 m/s | 2,101 kWh | $395 |
| February | 6.57 m/s | 1,833 kWh | $345 |
| March | 6.50 m/s | 1,991 kWh | $375 |
| April | 6.69 m/s | 2,039 kWh | $384 |
| May | 5.65 m/s | 1,456 kWh | $274 |
| June | 5.00 m/s | 1,028 kWh | $193 |
| July | 4.32 m/s | 705 kWh | $133 |
| August | 4.29 m/s | 692 kWh | $130 |
| September | 4.85 m/s | 950 kWh | $179 |
| October | 5.94 m/s | 1,633 kWh | $307 |
| November | 6.36 m/s | 1,840 kWh | $346 |
| December | 6.40 m/s | 1,924 kWh | $362 |
What a taller tower would buy
Measured at 10 m the wind in Darke County averages 4.46 m/s; at 50 m it is 6.5 m/s. That gives a shear exponent of 0.234, typical of ordinary open country. Going from 20 m to 50 m takes output from 14,226 to 23,407 kWh a year, 65% 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 | 5.25 m/s | 14,226 kWh | 37 years |
| 30 m | 5.77 m/s | 17,988 kWh | 30 years |
| 40 m | 6.17 m/s | 20,960 kWh | 25 years |
| 50 m | 6.5 m/s | 23,407 kWh | 23 years |
Counties around Darke County
4 of the 6 closest counties are windier at turbine height; the windiest, Randolph County, averages 5.92 m/s.
- Randolph County, IN: 5.92 m/s, 19,112 kWh, payback 31 years (20 mi)
- Miami County, OH: 5.77 m/s, 18,006 kWh, payback 30 years (21 mi)
- Shelby County, OH: 5.92 m/s, 19,112 kWh, payback 28 years (26 mi)
- Preble County, OH: 5.33 m/s, 14,821 kWh, payback 36 years (27 mi)
- Wayne County, IN: 5.92 m/s, 19,112 kWh, payback 31 years (28 mi)
- Mercer County, OH: 5.92 m/s, 19,112 kWh, payback 28 years (28 mi)
Sun versus wind in Darke County
Darke County gets 3.94 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,150 kWh a year; one kW of the turbine above makes 1,801. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.6 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.