Wind Turbine Payback in Carter County, TN
Wind turbine payback in Carter 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 Carter County, TN averages 3.73 m/s (8.3 mph). A 10 kW turbine there would make about 5,297 kWh a year, worth $731 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 Carter County
A home turbine is not worth buying for savings in Carter County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.73 m/s here. Per kW, solar panels would make about 1,232 kWh a year here against the turbine's 530, so get a solar quote first.
What would have to change
- Power would have to cost 94¢/kWh, 6.8 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 3.73. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Carter County is the 2,261st 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 Carter County
March is the strongest month here, at 4.52 m/s and about 802 kWh. August is the weakest, 2.62 m/s and 137 kWh, so the best month makes 5.9 times the worst. November to March brings in 61% of the year's output in Carter County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.50 m/s | 794 kWh | $110 |
| February | 4.66 m/s | 791 kWh | $109 |
| March | 4.52 m/s | 802 kWh | $111 |
| April | 4.37 m/s | 704 kWh | $97 |
| May | 3.59 m/s | 397 kWh | $55 |
| June | 3.05 m/s | 226 kWh | $31 |
| July | 2.78 m/s | 169 kWh | $23 |
| August | 2.62 m/s | 137 kWh | $19 |
| September | 3.00 m/s | 214 kWh | $30 |
| October | 3.57 m/s | 392 kWh | $54 |
| November | 3.92 m/s | 506 kWh | $70 |
| December | 4.21 m/s | 653 kWh | $90 |
What a taller tower would buy
Measured at 10 m the wind in Carter County averages 2.46 m/s; at 50 m it is 4.52 m/s. That gives a shear exponent of 0.378, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 3,221 to 9,459 kWh a year, 194% 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 | 3.2 m/s | 3,221 kWh | over 100 years |
| 30 m | 3.73 m/s | 5,281 kWh | over 100 years |
| 40 m | 4.15 m/s | 7,378 kWh | 98 years |
| 50 m | 4.52 m/s | 9,459 kWh | 77 years |
Counties around Carter County
None of the 6 closest counties is windier than Carter County.
- Sullivan County, TN: 3.68 m/s, 5,077 kWh, payback over 100 years (18 mi)
- Avery County, NC: 3.37 m/s, 3,830 kWh, payback over 100 years (19 mi)
- Johnson County, TN: 3.73 m/s, 5,297 kWh, payback over 100 years (19 mi)
- Mitchell County, NC: 3.37 m/s, 3,830 kWh, payback over 100 years (19 mi)
- Washington County, TN: 3.68 m/s, 5,077 kWh, payback over 100 years (21 mi)
- Unicoi County, TN: 3.22 m/s, 3,299 kWh, payback over 100 years (21 mi)
Sun versus wind in Carter County
Carter 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 530. Kilowatt for kilowatt, panels make 2.3 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.