Wind Turbine Payback in Green County, KY
Wind turbine payback in Green 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 Green County, KY averages 4.45 m/s (10 mph). A 10 kW turbine there would make about 9,041 kWh a year, worth $1,284 at KY's 14.2¢/kWh. Against an installed cost of about $100,000, that is a payback of 78 years, and the turbine is built to last about 20.
What to do in Green County
A home turbine is not worth buying for savings in Green County unless your spot is far windier than the county average, 8.2 m/s at the hub against 4.45 m/s here. Per kW, solar panels would make about 1,212 kWh a year here against the turbine's 904, so get a solar quote first.
What would have to change
- Power would have to cost 55¢/kWh, 3.9 times what KY pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 4.45. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of KY
Green County is the 1,778th 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 Green County
March is the strongest month here, at 5.26 m/s and about 1,216 kWh. August is the weakest, 3.32 m/s and 310 kWh, so the best month makes 3.9 times the worst. November to March brings in 56% of the year's output in Green County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.18 m/s | 1,170 kWh | $166 |
| February | 5.22 m/s | 1,080 kWh | $153 |
| March | 5.26 m/s | 1,216 kWh | $173 |
| April | 5.28 m/s | 1,192 kWh | $169 |
| May | 4.35 m/s | 718 kWh | $102 |
| June | 3.74 m/s | 439 kWh | $62 |
| July | 3.36 m/s | 323 kWh | $46 |
| August | 3.32 m/s | 310 kWh | $44 |
| September | 3.71 m/s | 427 kWh | $61 |
| October | 4.37 m/s | 727 kWh | $103 |
| November | 4.75 m/s | 897 kWh | $127 |
| December | 4.89 m/s | 1,002 kWh | $142 |
What a taller tower would buy
Measured at 10 m the wind in Green County averages 3.2 m/s; at 50 m it is 5.19 m/s. That gives a shear exponent of 0.300, typical of ordinary open country. Going from 20 m to 50 m takes output from 6,292 to 13,837 kWh a year, 120% 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 | 3.94 m/s | 6,292 kWh | over 100 years |
| 30 m | 4.45 m/s | 9,057 kWh | 78 years |
| 40 m | 4.85 m/s | 11,563 kWh | 61 years |
| 50 m | 5.19 m/s | 13,837 kWh | 51 years |
Counties around Green County
None of the 6 closest counties is windier than Green County.
- Taylor County, KY: 4.45 m/s, 9,041 kWh, payback 78 years (13 mi)
- Adair County, KY: 4 m/s, 6,577 kWh, payback over 100 years (18 mi)
- Hart County, KY: 4.45 m/s, 9,041 kWh, payback 78 years (19 mi)
- Larue County, KY: 4.45 m/s, 9,041 kWh, payback 78 years (20 mi)
- Metcalfe County, KY: 4.28 m/s, 8,064 kWh, payback 87 years (20 mi)
- Marion County, KY: 4.07 m/s, 6,934 kWh, payback over 100 years (24 mi)
Sun versus wind in Green County
Green 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 904. Kilowatt for kilowatt, panels make 1.3 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.