Wind Turbine Payback in Marion County, KY
Wind turbine payback in Marion 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 Marion County, KY averages 4.07 m/s (9.1 mph). A 10 kW turbine there would make about 6,934 kWh a year, worth $985 at KY's 14.2¢/kWh. Against an installed cost of about $100,000, that is a payback of over 100 years, and the turbine is built to last about 20.
What to do in Marion County
A home turbine is not worth buying for savings in Marion County unless your spot is far windier than the county average, 8.2 m/s at the hub against 4.07 m/s here. Per kW, solar panels would make about 1,212 kWh a year here against the turbine's 693, so get a solar quote first.
What would have to change
- Power would have to cost 72¢/kWh, 5.1 times what KY pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 4.07. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of KY
Marion County is the 2,014th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in KY is Fulton County at 5.54 m/s, payback 43 years.
Month by month in Marion County
March is the strongest month here, at 4.79 m/s and about 946 kWh. August is the weakest, 3.06 m/s and 238 kWh, so the best month makes 4.0 times the worst. November to March brings in 57% of the year's output in Marion County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.76 m/s | 933 kWh | $132 |
| February | 4.82 m/s | 871 kWh | $124 |
| March | 4.79 m/s | 946 kWh | $134 |
| April | 4.76 m/s | 902 kWh | $128 |
| May | 3.93 m/s | 530 kWh | $75 |
| June | 3.42 m/s | 331 kWh | $47 |
| July | 3.12 m/s | 253 kWh | $36 |
| August | 3.06 m/s | 238 kWh | $34 |
| September | 3.41 m/s | 329 kWh | $47 |
| October | 4.01 m/s | 561 kWh | $80 |
| November | 4.33 m/s | 686 kWh | $97 |
| December | 4.50 m/s | 792 kWh | $112 |
What a taller tower would buy
Measured at 10 m the wind in Marion County averages 2.75 m/s; at 50 m it is 4.89 m/s. That gives a shear exponent of 0.358, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 4,418 to 11,800 kWh a year, 167% 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 | 3.52 m/s | 4,418 kWh | over 100 years |
| 30 m | 4.07 m/s | 6,948 kWh | over 100 years |
| 40 m | 4.51 m/s | 9,426 kWh | 75 years |
| 50 m | 4.89 m/s | 11,800 kWh | 60 years |
Counties around Marion County
5 of the 6 closest counties are windier at turbine height; the windiest, Nelson County, averages 4.63 m/s.
- Taylor County, KY: 4.45 m/s, 9,041 kWh, payback 78 years (13 mi)
- Washington County, KY: 4.62 m/s, 10,070 kWh, payback 70 years (15 mi)
- Nelson County, KY: 4.63 m/s, 10,132 kWh, payback 70 years (20 mi)
- Boyle County, KY: 4.07 m/s, 6,934 kWh, payback over 100 years (22 mi)
- Larue County, KY: 4.45 m/s, 9,041 kWh, payback 78 years (23 mi)
- Green County, KY: 4.45 m/s, 9,041 kWh, payback 78 years (24 mi)
Sun versus wind in Marion County
Marion County gets 4.15 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,212 kWh a year; one kW of the turbine above makes 693. Kilowatt for kilowatt, panels make 1.7 times as much here as the turbine. 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.