Wind Turbine Payback in Franklin County, AL
Wind turbine payback in Franklin 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 Franklin County, AL averages 3.31 m/s (7.4 mph). A 10 kW turbine there would make about 3,612 kWh a year, worth $596 at AL's 16.51¢/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 Franklin County
A home turbine is not worth buying for savings in Franklin County unless your spot is far windier than the county average, 7.5 m/s at the hub against 3.31 m/s here. Per kW, solar panels would make about 1,296 kWh a year here against the turbine's 361, so get a solar quote first.
What would have to change
- Power would have to cost 138¢/kWh, 8.4 times what AL pays now.
- Or the average wind at the hub would have to be 7.5 m/s instead of 3.31. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of AL
Franklin County is the 2,729th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in AL is Mobile County at 4.72 m/s, payback 57 years.
Month by month in Franklin County
March is the strongest month here, at 3.91 m/s and about 522 kWh. July is the weakest, 2.45 m/s and 106 kWh, so the best month makes 4.9 times the worst. November to March brings in 58% of the year's output in Franklin County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.75 m/s | 459 kWh | $76 |
| February | 3.92 m/s | 474 kWh | $78 |
| March | 3.91 m/s | 522 kWh | $86 |
| April | 3.86 m/s | 483 kWh | $80 |
| May | 3.21 m/s | 278 kWh | $46 |
| June | 2.70 m/s | 147 kWh | $24 |
| July | 2.45 m/s | 106 kWh | $18 |
| August | 2.52 m/s | 119 kWh | $20 |
| September | 2.97 m/s | 206 kWh | $34 |
| October | 3.28 m/s | 297 kWh | $49 |
| November | 3.55 m/s | 371 kWh | $61 |
| December | 3.59 m/s | 400 kWh | $66 |
What a taller tower would buy
Measured at 10 m the wind in Franklin County averages 2.01 m/s; at 50 m it is 4.17 m/s. That gives a shear exponent of 0.453, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,928 to 7,461 kWh a year, 287% 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 | 2.75 m/s | 1,928 kWh | over 100 years |
| 30 m | 3.31 m/s | 3,607 kWh | over 100 years |
| 40 m | 3.77 m/s | 5,473 kWh | over 100 years |
| 50 m | 4.17 m/s | 7,461 kWh | 81 years |
Counties around Franklin County
2 of the 6 closest counties are windier at turbine height; the windiest, Colbert County, averages 3.87 m/s.
- Colbert County, AL: 3.87 m/s, 5,942 kWh, payback over 100 years (18 mi)
- Marion County, AL: 3.15 m/s, 3,067 kWh, payback over 100 years (21 mi)
- Lawrence County, AL: 3.87 m/s, 5,942 kWh, payback over 100 years (30 mi)
- Tishomingo County, MS: 3.31 m/s, 3,612 kWh, payback over 100 years (30 mi)
- Itawamba County, MS: 3.31 m/s, 3,612 kWh, payback over 100 years (32 mi)
- Winston County, AL: 3.15 m/s, 3,067 kWh, payback over 100 years (34 mi)
Sun versus wind in Franklin County
Franklin County gets 4.44 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,296 kWh a year; one kW of the turbine above makes 361. 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.