Wind Turbine Payback in Decatur County, TN
Wind turbine payback in Decatur 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 Decatur County, TN averages 3.28 m/s (7.3 mph). A 10 kW turbine there would make about 3,506 kWh a year, worth $484 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 Decatur County
A home turbine is not worth buying for savings in Decatur County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.28 m/s here. Per kW, solar panels would make about 1,279 kWh a year here against the turbine's 351, so get a solar quote first.
What would have to change
- Power would have to cost 143¢/kWh, 10.3 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 3.28. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Decatur County is the 2,773rd 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 Decatur County
March is the strongest month here, at 3.88 m/s and about 509 kWh. July is the weakest, 2.45 m/s and 106 kWh, so the best month makes 4.8 times the worst. November to March brings in 58% of the year's output in Decatur County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.73 m/s | 451 kWh | $62 |
| February | 3.88 m/s | 460 kWh | $63 |
| March | 3.88 m/s | 509 kWh | $70 |
| April | 3.85 m/s | 481 kWh | $66 |
| May | 3.19 m/s | 271 kWh | $37 |
| June | 2.70 m/s | 148 kWh | $20 |
| July | 2.45 m/s | 106 kWh | $15 |
| August | 2.51 m/s | 117 kWh | $16 |
| September | 2.87 m/s | 183 kWh | $25 |
| October | 3.24 m/s | 285 kWh | $39 |
| November | 3.50 m/s | 354 kWh | $49 |
| December | 3.57 m/s | 393 kWh | $54 |
What a taller tower would buy
Measured at 10 m the wind in Decatur County averages 1.96 m/s; at 50 m it is 4.16 m/s. That gives a shear exponent of 0.468, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,820 to 7,408 kWh a year, 307% 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 | 1,820 kWh | over 100 years |
| 30 m | 3.28 m/s | 3,490 kWh | over 100 years |
| 40 m | 3.75 m/s | 5,375 kWh | over 100 years |
| 50 m | 4.16 m/s | 7,408 kWh | 98 years |
Counties around Decatur County
4 of the 6 closest counties are windier at turbine height; the windiest, Carroll County, averages 5.09 m/s.
- Perry County, TN: 3.28 m/s, 3,506 kWh, payback over 100 years (14 mi)
- Henderson County, TN: 3.28 m/s, 3,506 kWh, payback over 100 years (16 mi)
- Hardin County, TN: 3.44 m/s, 4,094 kWh, payback over 100 years (28 mi)
- Wayne County, TN: 3.44 m/s, 4,094 kWh, payback over 100 years (30 mi)
- Chester County, TN: 4.34 m/s, 8,403 kWh, payback 86 years (31 mi)
- Carroll County, TN: 5.09 m/s, 13,146 kWh, payback 55 years (32 mi)
Sun versus wind in Decatur County
Decatur County gets 4.38 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,279 kWh a year; one kW of the turbine above makes 351. Kilowatt for kilowatt, panels make 3.6 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.