Wind Turbine Payback in Unicoi County, TN
Wind turbine payback in Unicoi 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 Unicoi County, TN averages 3.22 m/s (7.2 mph). A 10 kW turbine there would make about 3,299 kWh a year, worth $455 at TN's 13.8¢/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 Unicoi County
A home turbine is not worth buying for savings in Unicoi County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.22 m/s here. Per kW, solar panels would make about 1,232 kWh a year here against the turbine's 330, so get a solar quote first.
What would have to change
- Power would have to cost 152¢/kWh, 11.0 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 3.22. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Unicoi County is the 2,857th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in TN is Lake County at 5.54 m/s, payback 44 years.
Month by month in Unicoi County
March is the strongest month here, at 3.93 m/s and about 529 kWh. August is the weakest, 2.26 m/s and 77 kWh, so the best month makes 6.9 times the worst. November to March brings in 62% of the year's output in Unicoi County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.91 m/s | 519 kWh | $72 |
| February | 4.03 m/s | 518 kWh | $71 |
| March | 3.93 m/s | 529 kWh | $73 |
| April | 3.79 m/s | 459 kWh | $63 |
| May | 3.12 m/s | 251 kWh | $35 |
| June | 2.63 m/s | 133 kWh | $18 |
| July | 2.40 m/s | 98 kWh | $14 |
| August | 2.26 m/s | 77 kWh | $11 |
| September | 2.59 m/s | 127 kWh | $18 |
| October | 3.08 m/s | 243 kWh | $34 |
| November | 3.36 m/s | 311 kWh | $43 |
| December | 3.61 m/s | 405 kWh | $56 |
What a taller tower would buy
Measured at 10 m the wind in Unicoi County averages 2.02 m/s; at 50 m it is 4 m/s. That gives a shear exponent of 0.424, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,827 to 6,577 kWh a year, 260% 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 | 2.71 m/s | 1,827 kWh | over 100 years |
| 30 m | 3.22 m/s | 3,303 kWh | over 100 years |
| 40 m | 3.64 m/s | 4,900 kWh | over 100 years |
| 50 m | 4 m/s | 6,577 kWh | over 100 years |
Counties around Unicoi County
4 of the 6 closest counties are windier at turbine height; the windiest, Carter County, averages 3.73 m/s.
- Washington County, TN: 3.68 m/s, 5,077 kWh, payback over 100 years (14 mi)
- Mitchell County, NC: 3.37 m/s, 3,830 kWh, payback over 100 years (15 mi)
- Yancey County, NC: 3.22 m/s, 3,299 kWh, payback over 100 years (16 mi)
- Carter County, TN: 3.73 m/s, 5,297 kWh, payback over 100 years (21 mi)
- Madison County, NC: 3.22 m/s, 3,299 kWh, payback over 100 years (23 mi)
- Greene County, TN: 3.3 m/s, 3,577 kWh, payback over 100 years (25 mi)
Sun versus wind in Unicoi County
Unicoi County gets 4.22 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,232 kWh a year; one kW of the turbine above makes 330. Kilowatt for kilowatt, panels make 3.7 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.