Wind Turbine Payback in Graves County, KY
Wind turbine payback in Graves 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 Graves County, KY averages 5.26 m/s (11.8 mph). A 10 kW turbine there would make about 14,327 kWh a year, worth $2,034 at KY's 14.2¢/kWh. Against an installed cost of about $100,000, that is a payback of 49 years, and the turbine is built to last about 20.
What to do in Graves County
A home turbine is not worth buying for savings in Graves County unless your spot is far windier than the county average, 8.2 m/s at the hub against 5.26 m/s here. Per kW, solar panels would make about 1,250 kWh a year here against the turbine's 1,433, so get a solar quote first.
What would have to change
- Power would have to cost 35¢/kWh, 2.5 times what KY pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 5.26. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of KY
Graves County is the 1,339th 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 Graves County
April is the strongest month here, at 6.31 m/s and about 1,806 kWh. July is the weakest, 3.92 m/s and 525 kWh, so the best month makes 3.4 times the worst. November to March brings in 54% of the year's output in Graves County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.94 m/s | 1,634 kWh | $232 |
| February | 6.02 m/s | 1,526 kWh | $217 |
| March | 6.16 m/s | 1,772 kWh | $252 |
| April | 6.31 m/s | 1,806 kWh | $256 |
| May | 5.26 m/s | 1,218 kWh | $173 |
| June | 4.37 m/s | 703 kWh | $100 |
| July | 3.92 m/s | 525 kWh | $75 |
| August | 3.96 m/s | 543 kWh | $77 |
| September | 4.50 m/s | 767 kWh | $109 |
| October | 5.25 m/s | 1,213 kWh | $172 |
| November | 5.74 m/s | 1,464 kWh | $208 |
| December | 5.75 m/s | 1,519 kWh | $216 |
What a taller tower would buy
Measured at 10 m the wind in Graves County averages 3.97 m/s; at 50 m it is 6 m/s. That gives a shear exponent of 0.257, typical of ordinary open country. Going from 20 m to 50 m takes output from 10,833 to 19,704 kWh a year, 82% 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 | 4.74 m/s | 10,833 kWh | 65 years |
| 30 m | 5.26 m/s | 14,339 kWh | 49 years |
| 40 m | 5.67 m/s | 17,240 kWh | 41 years |
| 50 m | 6 m/s | 19,704 kWh | 36 years |
Counties around Graves County
None of the 6 closest counties is windier than Graves County.
- Hickman County, KY: 5.26 m/s, 14,327 kWh, payback 49 years (18 mi)
- Carlisle County, KY: 5.03 m/s, 12,737 kWh, payback 55 years (20 mi)
- Marshall County, KY: 4.94 m/s, 12,132 kWh, payback 58 years (21 mi)
- Calloway County, KY: 4.17 m/s, 7,461 kWh, payback 94 years (22 mi)
- McCracken County, KY: 5.03 m/s, 12,737 kWh, payback 55 years (23 mi)
- Weakley County, TN: 5.26 m/s, 14,327 kWh, payback 51 years (29 mi)
Sun versus wind in Graves County
Graves County gets 4.28 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,250 kWh a year; one kW of the turbine above makes 1,433. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.1 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.