Wind Turbine Payback in Shelby County, TN
Wind turbine payback in Shelby 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 Shelby County, TN averages 5.13 m/s (11.5 mph). A 10 kW turbine there would make about 13,421 kWh a year, worth $1,852 at TN's 13.8¢/kWh. Against an installed cost of about $100,000, that is a payback of 54 years, and the turbine is built to last about 20.
What to do in Shelby County
A home turbine is not worth buying for savings in Shelby County unless your spot is far windier than the county average, 8.4 m/s at the hub against 5.13 m/s here. Per kW, solar panels would make about 1,291 kWh a year here against the turbine's 1,342, so get a solar quote first.
What would have to change
- Power would have to cost 37¢/kWh, 2.7 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 5.13. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Shelby County is the 1,400th 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 Shelby County
March is the strongest month here, at 6.02 m/s and about 1,689 kWh. July is the weakest, 3.72 m/s and 446 kWh, so the best month makes 3.8 times the worst. November to March brings in 55% of the year's output in Shelby County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.86 m/s | 1,584 kWh | $219 |
| February | 5.97 m/s | 1,496 kWh | $206 |
| March | 6.02 m/s | 1,689 kWh | $233 |
| April | 6.09 m/s | 1,672 kWh | $231 |
| May | 5.11 m/s | 1,130 kWh | $156 |
| June | 4.24 m/s | 647 kWh | $89 |
| July | 3.72 m/s | 446 kWh | $62 |
| August | 3.82 m/s | 486 kWh | $67 |
| September | 4.46 m/s | 750 kWh | $104 |
| October | 5.09 m/s | 1,114 kWh | $154 |
| November | 5.64 m/s | 1,401 kWh | $193 |
| December | 5.67 m/s | 1,464 kWh | $202 |
What a taller tower would buy
Measured at 10 m the wind in Shelby County averages 3.87 m/s; at 50 m it is 5.85 m/s. That gives a shear exponent of 0.257, typical of ordinary open country. Going from 20 m to 50 m takes output from 10,086 to 18,595 kWh a year, 84% 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 | 4.62 m/s | 10,086 kWh | 72 years |
| 30 m | 5.13 m/s | 13,423 kWh | 54 years |
| 40 m | 5.52 m/s | 16,210 kWh | 45 years |
| 50 m | 5.85 m/s | 18,595 kWh | 39 years |
Counties around Shelby County
1 of the 6 closest counties is windier at turbine height; the windiest, Tipton County, averages 5.35 m/s.
- DeSoto County, MS: 5.13 m/s, 13,421 kWh, payback 50 years (22 mi)
- Crittenden County, AR: 5.13 m/s, 13,421 kWh, payback 54 years (23 mi)
- Tipton County, TN: 5.35 m/s, 14,963 kWh, payback 48 years (23 mi)
- Fayette County, TN: 4.35 m/s, 8,460 kWh, payback 86 years (27 mi)
- Marshall County, MS: 4.35 m/s, 8,460 kWh, payback 79 years (36 mi)
- Tate County, MS: 4.85 m/s, 11,537 kWh, payback 58 years (37 mi)
Sun versus wind in Shelby County
Shelby County gets 4.42 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,291 kWh a year; one kW of the turbine above makes 1,342. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.0 times. 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.