Wind Turbine Payback in McNairy County, TN
Wind turbine payback in McNairy 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 McNairy County, TN averages 3.47 m/s (7.8 mph). A 10 kW turbine there would make about 4,211 kWh a year, worth $581 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 McNairy County
A home turbine is not worth buying for savings in McNairy County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.47 m/s here. Per kW, solar panels would make about 1,279 kWh a year here against the turbine's 421, so get a solar quote first.
What would have to change
- Power would have to cost 119¢/kWh, 8.6 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 3.47. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
McNairy County is the 2,548th 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 McNairy County
March is the strongest month here, at 4.12 m/s and about 609 kWh. July is the weakest, 2.56 m/s and 126 kWh, so the best month makes 4.8 times the worst. November to March brings in 57% of the year's output in McNairy County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.96 m/s | 540 kWh | $75 |
| February | 4.09 m/s | 541 kWh | $75 |
| March | 4.12 m/s | 609 kWh | $84 |
| April | 4.09 m/s | 579 kWh | $80 |
| May | 3.41 m/s | 338 kWh | $47 |
| June | 2.87 m/s | 183 kWh | $25 |
| July | 2.56 m/s | 126 kWh | $17 |
| August | 2.62 m/s | 136 kWh | $19 |
| September | 3.05 m/s | 226 kWh | $31 |
| October | 3.42 m/s | 341 kWh | $47 |
| November | 3.71 m/s | 427 kWh | $59 |
| December | 3.79 m/s | 472 kWh | $65 |
What a taller tower would buy
Measured at 10 m the wind in McNairy County averages 2.15 m/s; at 50 m it is 4.33 m/s. That gives a shear exponent of 0.435, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 2,333 to 8,346 kWh a year, 258% 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 | 2.91 m/s | 2,333 kWh | over 100 years |
| 30 m | 3.47 m/s | 4,200 kWh | over 100 years |
| 40 m | 3.93 m/s | 6,228 kWh | over 100 years |
| 50 m | 4.33 m/s | 8,346 kWh | 87 years |
Counties around McNairy County
2 of the 6 closest counties are windier at turbine height; the windiest, Chester County, averages 4.34 m/s.
- Chester County, TN: 4.34 m/s, 8,403 kWh, payback 86 years (17 mi)
- Alcorn County, MS: 3.47 m/s, 4,211 kWh, payback over 100 years (20 mi)
- Hardin County, TN: 3.44 m/s, 4,094 kWh, payback over 100 years (21 mi)
- Hardeman County, TN: 3.47 m/s, 4,211 kWh, payback over 100 years (24 mi)
- Madison County, TN: 4.34 m/s, 8,403 kWh, payback 86 years (33 mi)
- Henderson County, TN: 3.28 m/s, 3,506 kWh, payback over 100 years (35 mi)
Sun versus wind in McNairy County
McNairy 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 421. Kilowatt for kilowatt, panels make 3.0 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.