Wind Turbine Payback in Macon County, TN
Wind turbine payback in Macon 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 Macon County, TN averages 4.45 m/s (10 mph). A 10 kW turbine there would make about 9,041 kWh a year, worth $1,248 at TN's 13.8¢/kWh. Against an installed cost of about $100,000, that is a payback of 80 years, and the turbine is built to last about 20.
What to do in Macon County
A home turbine is not worth buying for savings in Macon County unless your spot is far windier than the county average, 8.4 m/s at the hub against 4.45 m/s here. Per kW, solar panels would make about 1,235 kWh a year here against the turbine's 904, so get a solar quote first.
What would have to change
- Power would have to cost 55¢/kWh, 4.0 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 4.45. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Macon County is the 1,778th 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 Macon County
March is the strongest month here, at 5.34 m/s and about 1,262 kWh. July is the weakest, 3.24 m/s and 286 kWh, so the best month makes 4.4 times the worst. November to March brings in 57% of the year's output in Macon County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.16 m/s | 1,160 kWh | $160 |
| February | 5.28 m/s | 1,107 kWh | $153 |
| March | 5.34 m/s | 1,262 kWh | $174 |
| April | 5.33 m/s | 1,217 kWh | $168 |
| May | 4.33 m/s | 709 kWh | $98 |
| June | 3.63 m/s | 401 kWh | $55 |
| July | 3.24 m/s | 286 kWh | $39 |
| August | 3.27 m/s | 293 kWh | $40 |
| September | 3.74 m/s | 438 kWh | $60 |
| October | 4.37 m/s | 730 kWh | $101 |
| November | 4.82 m/s | 932 kWh | $129 |
| December | 4.95 m/s | 1,036 kWh | $143 |
What a taller tower would buy
Measured at 10 m the wind in Macon County averages 3.21 m/s; at 50 m it is 5.18 m/s. That gives a shear exponent of 0.297, typical of ordinary open country. Going from 20 m to 50 m takes output from 6,308 to 13,768 kWh a year, 118% 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 | 3.95 m/s | 6,308 kWh | over 100 years |
| 30 m | 4.45 m/s | 9,046 kWh | 80 years |
| 40 m | 4.85 m/s | 11,523 kWh | 63 years |
| 50 m | 5.18 m/s | 13,768 kWh | 53 years |
Counties around Macon County
1 of the 6 closest counties is windier at turbine height; the windiest, Allen County, averages 4.47 m/s.
- Trousdale County, TN: 4.45 m/s, 9,041 kWh, payback 80 years (13 mi)
- Allen County, KY: 4.47 m/s, 9,160 kWh, payback 77 years (18 mi)
- Smith County, TN: 4.45 m/s, 9,041 kWh, payback 80 years (20 mi)
- Monroe County, KY: 3.62 m/s, 4,820 kWh, payback over 100 years (20 mi)
- Jackson County, TN: 3.62 m/s, 4,820 kWh, payback over 100 years (22 mi)
- Clay County, TN: 3.62 m/s, 4,820 kWh, payback over 100 years (25 mi)
Sun versus wind in Macon County
Macon 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 904. Kilowatt for kilowatt, panels make 1.4 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.