Wind Turbine Payback in Sumter County, AL
Wind turbine payback in Sumter 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 Sumter County, AL averages 3.17 m/s (7.1 mph). A 10 kW turbine there would make about 3,132 kWh a year, worth $517 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 Sumter County
A home turbine is not worth buying for savings in Sumter County unless your spot is far windier than the county average, 7.5 m/s at the hub against 3.17 m/s here. Per kW, solar panels would make about 1,337 kWh a year here against the turbine's 313, so get a solar quote first.
What would have to change
- Power would have to cost 160¢/kWh, 9.7 times what AL pays now.
- Or the average wind at the hub would have to be 7.5 m/s instead of 3.17. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of AL
Sumter County is the 2,915th 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 Sumter County
March is the strongest month here, at 3.62 m/s and about 410 kWh. July is the weakest, 2.47 m/s and 109 kWh, so the best month makes 3.8 times the worst. November to March brings in 55% of the year's output in Sumter County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.50 m/s | 368 kWh | $61 |
| February | 3.59 m/s | 360 kWh | $59 |
| March | 3.62 m/s | 410 kWh | $68 |
| April | 3.61 m/s | 392 kWh | $65 |
| May | 3.10 m/s | 246 kWh | $41 |
| June | 2.66 m/s | 140 kWh | $23 |
| July | 2.47 m/s | 109 kWh | $18 |
| August | 2.53 m/s | 121 kWh | $20 |
| September | 2.96 m/s | 204 kWh | $34 |
| October | 3.24 m/s | 285 kWh | $47 |
| November | 3.40 m/s | 323 kWh | $53 |
| December | 3.42 m/s | 342 kWh | $56 |
What a taller tower would buy
Measured at 10 m the wind in Sumter County averages 2 m/s; at 50 m it is 3.93 m/s. That gives a shear exponent of 0.420, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,737 to 6,231 kWh a year, 259% 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 | 2.67 m/s | 1,737 kWh | over 100 years |
| 30 m | 3.17 m/s | 3,136 kWh | over 100 years |
| 40 m | 3.58 m/s | 4,646 kWh | over 100 years |
| 50 m | 3.93 m/s | 6,231 kWh | 97 years |
Counties around Sumter County
3 of the 6 closest counties are windier at turbine height; the windiest, Kemper County, averages 3.27 m/s.
- Greene County, AL: 3.2 m/s, 3,232 kWh, payback over 100 years (22 mi)
- Kemper County, MS: 3.27 m/s, 3,471 kWh, payback over 100 years (27 mi)
- Lauderdale County, MS: 3.04 m/s, 2,721 kWh, payback over 100 years (30 mi)
- Marengo County, AL: 2.94 m/s, 2,427 kWh, payback over 100 years (34 mi)
- Hale County, AL: 2.97 m/s, 2,513 kWh, payback over 100 years (35 mi)
- Noxubee County, MS: 3.27 m/s, 3,471 kWh, payback over 100 years (41 mi)
Sun versus wind in Sumter County
Sumter County gets 4.58 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,337 kWh a year; one kW of the turbine above makes 313. Kilowatt for kilowatt, panels make 4.3 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.