Wind Turbine Payback in Sullivan County, TN
Wind turbine payback in Sullivan 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 Sullivan County, TN averages 3.68 m/s (8.2 mph). A 10 kW turbine there would make about 5,077 kWh a year, worth $701 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 Sullivan County
A home turbine is not worth buying for savings in Sullivan County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.68 m/s here. Per kW, solar panels would make about 1,232 kWh a year here against the turbine's 508, so get a solar quote first.
What would have to change
- Power would have to cost 98¢/kWh, 7.1 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 3.68. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Sullivan County is the 2,305th 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 Sullivan County
March is the strongest month here, at 4.45 m/s and about 768 kWh. August is the weakest, 2.66 m/s and 145 kWh, so the best month makes 5.3 times the worst. November to March brings in 59% of the year's output in Sullivan County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.32 m/s | 702 kWh | $97 |
| February | 4.49 m/s | 713 kWh | $98 |
| March | 4.45 m/s | 768 kWh | $106 |
| April | 4.34 m/s | 691 kWh | $95 |
| May | 3.57 m/s | 392 kWh | $54 |
| June | 3.04 m/s | 224 kWh | $31 |
| July | 2.79 m/s | 171 kWh | $24 |
| August | 2.66 m/s | 145 kWh | $20 |
| September | 3.06 m/s | 228 kWh | $31 |
| October | 3.56 m/s | 386 kWh | $53 |
| November | 3.87 m/s | 487 kWh | $67 |
| December | 4.09 m/s | 596 kWh | $82 |
What a taller tower would buy
Measured at 10 m the wind in Sullivan County averages 2.56 m/s; at 50 m it is 4.36 m/s. That gives a shear exponent of 0.331, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 3,297 to 8,517 kWh a year, 158% 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 | 3.22 m/s | 3,297 kWh | over 100 years |
| 30 m | 3.68 m/s | 5,085 kWh | over 100 years |
| 40 m | 4.05 m/s | 6,829 kWh | over 100 years |
| 50 m | 4.36 m/s | 8,517 kWh | 85 years |
Counties around Sullivan County
4 of the 6 closest counties are windier at turbine height; the windiest, Bristol city, averages 3.73 m/s.
- Bristol city, VA: 3.73 m/s, 5,297 kWh, payback over 100 years (11 mi)
- Washington County, TN: 3.68 m/s, 5,077 kWh, payback over 100 years (18 mi)
- Carter County, TN: 3.73 m/s, 5,297 kWh, payback over 100 years (18 mi)
- Scott County, VA: 3.68 m/s, 5,077 kWh, payback over 100 years (22 mi)
- Johnson County, TN: 3.73 m/s, 5,297 kWh, payback over 100 years (25 mi)
- Washington County, VA: 3.73 m/s, 5,297 kWh, payback over 100 years (25 mi)
Sun versus wind in Sullivan County
Sullivan 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 508. Kilowatt for kilowatt, panels make 2.4 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.