Wind Turbine Payback in Roane County, TN
Wind turbine payback in Roane 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 Roane County, TN averages 3.05 m/s (6.8 mph). A 10 kW turbine there would make about 2,751 kWh a year, worth $380 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 Roane County
A home turbine is not worth buying for savings in Roane County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.05 m/s here. Per kW, solar panels would make about 1,261 kWh a year here against the turbine's 275, so get a solar quote first.
What would have to change
- Power would have to cost 182¢/kWh, 13.2 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 3.05. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Roane County is the 3,024th 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 Roane County
March is the strongest month here, at 3.63 m/s and about 414 kWh. August is the weakest, 2.33 m/s and 87 kWh, so the best month makes 4.8 times the worst. November to March brings in 58% of the year's output in Roane County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.48 m/s | 361 kWh | $50 |
| February | 3.62 m/s | 371 kWh | $51 |
| March | 3.63 m/s | 414 kWh | $57 |
| April | 3.62 m/s | 398 kWh | $55 |
| May | 2.99 m/s | 219 kWh | $30 |
| June | 2.57 m/s | 123 kWh | $17 |
| July | 2.35 m/s | 91 kWh | $13 |
| August | 2.33 m/s | 87 kWh | $12 |
| September | 2.56 m/s | 122 kWh | $17 |
| October | 2.97 m/s | 213 kWh | $29 |
| November | 3.20 m/s | 266 kWh | $37 |
| December | 3.30 m/s | 303 kWh | $42 |
What a taller tower would buy
Measured at 10 m the wind in Roane County averages 1.88 m/s; at 50 m it is 3.82 m/s. That gives a shear exponent of 0.441, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,456 to 5,707 kWh a year, 292% 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 | 2.55 m/s | 1,456 kWh | over 100 years |
| 30 m | 3.05 m/s | 2,750 kWh | over 100 years |
| 40 m | 3.46 m/s | 4,179 kWh | over 100 years |
| 50 m | 3.82 m/s | 5,707 kWh | over 100 years |
Counties around Roane County
4 of the 6 closest counties are windier at turbine height; the windiest, Cumberland County, averages 3.18 m/s.
- Loudon County, TN: 3.07 m/s, 2,813 kWh, payback over 100 years (14 mi)
- Morgan County, TN: 3.05 m/s, 2,751 kWh, payback over 100 years (21 mi)
- Anderson County, TN: 3.05 m/s, 2,751 kWh, payback over 100 years (26 mi)
- Cumberland County, TN: 3.18 m/s, 3,165 kWh, payback over 100 years (27 mi)
- Meigs County, TN: 3.07 m/s, 2,813 kWh, payback over 100 years (28 mi)
- Rhea County, TN: 3.07 m/s, 2,813 kWh, payback over 100 years (29 mi)
Sun versus wind in Roane County
Roane County gets 4.32 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,261 kWh a year; one kW of the turbine above makes 275. Kilowatt for kilowatt, panels make 4.6 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.