Wind Turbine Payback in Simpson County, KY
Wind turbine payback in Simpson 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 Simpson County, KY averages 4.5 m/s (10.1 mph). A 10 kW turbine there would make about 9,339 kWh a year, worth $1,326 at KY's 14.2¢/kWh. Against an installed cost of about $100,000, that is a payback of 75 years, and the turbine is built to last about 20.
What to do in Simpson County
A home turbine is not worth buying for savings in Simpson County unless your spot is far windier than the county average, 8.2 m/s at the hub against 4.5 m/s here. Per kW, solar panels would make about 1,235 kWh a year here against the turbine's 934, so get a solar quote first.
What would have to change
- Power would have to cost 54¢/kWh, 3.8 times what KY pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 4.5. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of KY
Simpson County is the 1,743rd 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 Simpson County
March is the strongest month here, at 5.37 m/s and about 1,285 kWh. July is the weakest, 3.25 m/s and 288 kWh, so the best month makes 4.5 times the worst. November to March brings in 57% of the year's output in Simpson County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.21 m/s | 1,188 kWh | $169 |
| February | 5.29 m/s | 1,114 kWh | $158 |
| March | 5.37 m/s | 1,285 kWh | $182 |
| April | 5.37 m/s | 1,244 kWh | $177 |
| May | 4.38 m/s | 733 kWh | $104 |
| June | 3.66 m/s | 410 kWh | $58 |
| July | 3.25 m/s | 288 kWh | $41 |
| August | 3.32 m/s | 309 kWh | $44 |
| September | 3.83 m/s | 473 kWh | $67 |
| October | 4.47 m/s | 776 kWh | $110 |
| November | 4.89 m/s | 972 kWh | $138 |
| December | 5.00 m/s | 1,063 kWh | $151 |
What a taller tower would buy
Measured at 10 m the wind in Simpson County averages 3.23 m/s; at 50 m it is 5.25 m/s. That gives a shear exponent of 0.302, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 6,482 to 14,256 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 | 3.98 m/s | 6,482 kWh | over 100 years |
| 30 m | 4.5 m/s | 9,336 kWh | 75 years |
| 40 m | 4.91 m/s | 11,918 kWh | 59 years |
| 50 m | 5.25 m/s | 14,256 kWh | 49 years |
Counties around Simpson County
None of the 6 closest counties is windier than Simpson County.
- Logan County, KY: 4.38 m/s, 8,632 kWh, payback 82 years (18 mi)
- Warren County, KY: 4.47 m/s, 9,160 kWh, payback 77 years (20 mi)
- Sumner County, TN: 4.45 m/s, 9,041 kWh, payback 80 years (20 mi)
- Allen County, KY: 4.47 m/s, 9,160 kWh, payback 77 years (22 mi)
- Robertson County, TN: 4.5 m/s, 9,339 kWh, payback 78 years (22 mi)
- Butler County, KY: 4.38 m/s, 8,632 kWh, payback 82 years (33 mi)
Sun versus wind in Simpson County
Simpson County gets 4.23 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,235 kWh a year; one kW of the turbine above makes 934. 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.