Wind Turbine Payback in Marshall County, KY
Wind turbine payback in Marshall 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 Marshall County, KY averages 4.94 m/s (11.1 mph). A 10 kW turbine there would make about 12,132 kWh a year, worth $1,723 at KY's 14.2¢/kWh. Against an installed cost of about $100,000, that is a payback of 58 years, and the turbine is built to last about 20.
What to do in Marshall County
A home turbine is not worth buying for savings in Marshall County unless your spot is far windier than the county average, 8.2 m/s at the hub against 4.94 m/s here. Per kW, solar panels would make about 1,250 kWh a year here against the turbine's 1,213, so get a solar quote first.
What would have to change
- Power would have to cost 41¢/kWh, 2.9 times what KY pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 4.94. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of KY
Marshall County is the 1,482nd 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 Marshall County
April is the strongest month here, at 5.91 m/s and about 1,565 kWh. July is the weakest, 3.67 m/s and 429 kWh, so the best month makes 3.6 times the worst. November to March brings in 55% of the year's output in Marshall County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.67 m/s | 1,464 kWh | $208 |
| February | 5.72 m/s | 1,352 kWh | $192 |
| March | 5.82 m/s | 1,562 kWh | $222 |
| April | 5.91 m/s | 1,565 kWh | $222 |
| May | 4.88 m/s | 999 kWh | $142 |
| June | 4.11 m/s | 588 kWh | $83 |
| July | 3.67 m/s | 429 kWh | $61 |
| August | 3.71 m/s | 442 kWh | $63 |
| September | 4.17 m/s | 615 kWh | $87 |
| October | 4.91 m/s | 1,014 kWh | $144 |
| November | 5.34 m/s | 1,224 kWh | $174 |
| December | 5.42 m/s | 1,313 kWh | $186 |
What a taller tower would buy
Measured at 10 m the wind in Marshall County averages 3.72 m/s; at 50 m it is 5.63 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 9,034 to 16,980 kWh a year, 88% 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 | 4.45 m/s | 9,034 kWh | 78 years |
| 30 m | 4.94 m/s | 12,114 kWh | 58 years |
| 40 m | 5.32 m/s | 14,723 kWh | 48 years |
| 50 m | 5.63 m/s | 16,980 kWh | 42 years |
Counties around Marshall County
2 of the 6 closest counties are windier at turbine height; the windiest, Graves County, averages 5.26 m/s.
- Lyon County, KY: 4.94 m/s, 12,132 kWh, payback 58 years (17 mi)
- Calloway County, KY: 4.17 m/s, 7,461 kWh, payback 94 years (18 mi)
- Graves County, KY: 5.26 m/s, 14,327 kWh, payback 49 years (21 mi)
- Livingston County, KY: 4.94 m/s, 12,132 kWh, payback 58 years (23 mi)
- McCracken County, KY: 5.03 m/s, 12,737 kWh, payback 55 years (24 mi)
- Trigg County, KY: 4.94 m/s, 12,132 kWh, payback 58 years (27 mi)
Sun versus wind in Marshall County
Marshall 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 1,213. Kilowatt for kilowatt, panels make 1.0 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.