Wind Turbine Payback in Clay County, AL
Wind turbine payback in Clay 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 Clay County, AL averages 3.16 m/s (7.1 mph). A 10 kW turbine there would make about 3,099 kWh a year, worth $512 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 Clay County
A home turbine is not worth buying for savings in Clay County unless your spot is far windier than the county average, 7.5 m/s at the hub against 3.16 m/s here. Per kW, solar panels would make about 1,314 kWh a year here against the turbine's 310, so get a solar quote first.
What would have to change
- Power would have to cost 161¢/kWh, 9.8 times what AL pays now.
- Or the average wind at the hub would have to be 7.5 m/s instead of 3.16. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of AL
Clay County is the 2,928th 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 Clay County
March is the strongest month here, at 3.64 m/s and about 416 kWh. July is the weakest, 2.41 m/s and 100 kWh, so the best month makes 4.2 times the worst. November to March brings in 57% of the year's output in Clay County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.58 m/s | 394 kWh | $65 |
| February | 3.62 m/s | 368 kWh | $61 |
| March | 3.64 m/s | 416 kWh | $69 |
| April | 3.58 m/s | 384 kWh | $63 |
| May | 3.06 m/s | 235 kWh | $39 |
| June | 2.60 m/s | 129 kWh | $21 |
| July | 2.41 m/s | 100 kWh | $17 |
| August | 2.43 m/s | 104 kWh | $17 |
| September | 2.88 m/s | 186 kWh | $31 |
| October | 3.21 m/s | 276 kWh | $46 |
| November | 3.44 m/s | 337 kWh | $56 |
| December | 3.46 m/s | 354 kWh | $58 |
What a taller tower would buy
Measured at 10 m the wind in Clay County averages 1.89 m/s; at 50 m it is 4.01 m/s. That gives a shear exponent of 0.467, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,597 to 6,628 kWh a year, 315% 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 | 2.61 m/s | 1,597 kWh | over 100 years |
| 30 m | 3.16 m/s | 3,096 kWh | over 100 years |
| 40 m | 3.61 m/s | 4,791 kWh | over 100 years |
| 50 m | 4.01 m/s | 6,628 kWh | 91 years |
Counties around Clay County
3 of the 6 closest counties are windier at turbine height; the windiest, Coosa County, averages 3.22 m/s.
- Talladega County, AL: 3.21 m/s, 3,265 kWh, payback over 100 years (19 mi)
- Randolph County, AL: 3.16 m/s, 3,099 kWh, payback over 100 years (23 mi)
- Tallapoosa County, AL: 3.11 m/s, 2,938 kWh, payback over 100 years (28 mi)
- Coosa County, AL: 3.22 m/s, 3,299 kWh, payback over 100 years (32 mi)
- Cleburne County, AL: 3.16 m/s, 3,099 kWh, payback over 100 years (34 mi)
- Calhoun County, AL: 3.22 m/s, 3,299 kWh, payback over 100 years (35 mi)
Sun versus wind in Clay County
Clay County gets 4.5 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,314 kWh a year; one kW of the turbine above makes 310. Kilowatt for kilowatt, panels make 4.2 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.