Wind Turbine Payback in Marshall County, AL
Wind turbine payback in Marshall 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 Marshall County, AL averages 3.58 m/s (8 mph). A 10 kW turbine there would make about 4,653 kWh a year, worth $768 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 Marshall County
A home turbine is not worth buying for savings in Marshall County unless your spot is far windier than the county average, 7.5 m/s at the hub against 3.58 m/s here. Per kW, solar panels would make about 1,294 kWh a year here against the turbine's 465, so get a solar quote first.
What would have to change
- Power would have to cost 107¢/kWh, 6.5 times what AL pays now.
- Or the average wind at the hub would have to be 7.5 m/s instead of 3.58. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of AL
Marshall County is the 2,429th 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 Marshall County
March is the strongest month here, at 4.21 m/s and about 654 kWh. July is the weakest, 2.60 m/s and 133 kWh, so the best month makes 4.9 times the worst. November to March brings in 58% of the year's output in Marshall County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.14 m/s | 620 kWh | $102 |
| February | 4.25 m/s | 604 kWh | $100 |
| March | 4.21 m/s | 654 kWh | $108 |
| April | 4.16 m/s | 610 kWh | $101 |
| May | 3.43 m/s | 344 kWh | $57 |
| June | 2.89 m/s | 188 kWh | $31 |
| July | 2.60 m/s | 133 kWh | $22 |
| August | 2.69 m/s | 151 kWh | $25 |
| September | 3.15 m/s | 251 kWh | $41 |
| October | 3.57 m/s | 391 kWh | $65 |
| November | 3.87 m/s | 490 kWh | $81 |
| December | 3.97 m/s | 544 kWh | $90 |
What a taller tower would buy
Measured at 10 m the wind in Marshall County averages 2.37 m/s; at 50 m it is 4.33 m/s. That gives a shear exponent of 0.374, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 2,824 to 8,346 kWh a year, 196% 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 | 3.07 m/s | 2,824 kWh | over 100 years |
| 30 m | 3.58 m/s | 4,640 kWh | over 100 years |
| 40 m | 3.98 m/s | 6,494 kWh | 93 years |
| 50 m | 4.33 m/s | 8,346 kWh | 73 years |
Counties around Marshall County
2 of the 6 closest counties are windier at turbine height; the windiest, Morgan County, averages 3.84 m/s.
- Etowah County, AL: 3.3 m/s, 3,577 kWh, payback over 100 years (24 mi)
- Blount County, AL: 3.23 m/s, 3,333 kWh, payback over 100 years (27 mi)
- DeKalb County, AL: 3.18 m/s, 3,165 kWh, payback over 100 years (31 mi)
- Morgan County, AL: 3.84 m/s, 5,800 kWh, payback over 100 years (32 mi)
- Cullman County, AL: 3.23 m/s, 3,333 kWh, payback over 100 years (34 mi)
- Madison County, AL: 3.8 m/s, 5,614 kWh, payback over 100 years (34 mi)
Sun versus wind in Marshall County
Marshall County gets 4.43 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,294 kWh a year; one kW of the turbine above makes 465. Kilowatt for kilowatt, panels make 2.8 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.