Wind Turbine Payback in Davis County, IA
Wind turbine payback in Davis 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 Davis County, IA averages 5.42 m/s (12.1 mph). A 10 kW turbine there would make about 15,462 kWh a year, worth $2,250 at IA's 14.55¢/kWh. Against an installed cost of about $100,000, that is a payback of 45 years, and the turbine is built to last about 20.
What to do in Davis County
A home turbine is not worth buying for savings in Davis County unless your spot is far windier than the county average, 8.1 m/s at the hub against 5.42 m/s here. Per kW, solar panels would make about 1,194 kWh a year here against the turbine's 1,546, so get a solar quote first.
What would have to change
- Power would have to cost 32¢/kWh, 2.2 times what IA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 5.42. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IA
Davis County is the 1,264th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in IA is Dickinson County at 6.59 m/s, payback 29 years.
Month by month in Davis County
April is the strongest month here, at 6.24 m/s and about 1,768 kWh. August is the weakest, 4.19 m/s and 641 kWh, so the best month makes 2.8 times the worst. November to March brings in 51% of the year's output in Davis County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.02 m/s | 1,684 kWh | $245 |
| February | 6.01 m/s | 1,516 kWh | $221 |
| March | 6.13 m/s | 1,756 kWh | $255 |
| April | 6.24 m/s | 1,768 kWh | $257 |
| May | 5.40 m/s | 1,300 kWh | $189 |
| June | 4.85 m/s | 948 kWh | $138 |
| July | 4.25 m/s | 669 kWh | $97 |
| August | 4.19 m/s | 641 kWh | $93 |
| September | 4.88 m/s | 966 kWh | $141 |
| October | 5.58 m/s | 1,412 kWh | $205 |
| November | 5.90 m/s | 1,556 kWh | $226 |
| December | 5.74 m/s | 1,509 kWh | $220 |
What a taller tower would buy
Measured at 10 m the wind in Davis County averages 4.04 m/s; at 50 m it is 6.22 m/s. That gives a shear exponent of 0.268, typical of ordinary open country. Going from 20 m to 50 m takes output from 11,640 to 21,336 kWh a year, 83% 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 | 4.87 m/s | 11,640 kWh | 59 years |
| 30 m | 5.42 m/s | 15,492 kWh | 44 years |
| 40 m | 5.86 m/s | 18,661 kWh | 37 years |
| 50 m | 6.22 m/s | 21,336 kWh | 32 years |
Counties around Davis County
5 of the 6 closest counties are windier at turbine height; the windiest, Van Buren County, averages 5.97 m/s.
- Wapello County, IA: 5.96 m/s, 19,408 kWh, payback 35 years (20 mi)
- Schuyler County, MO: 5.42 m/s, 15,462 kWh, payback 45 years (20 mi)
- Van Buren County, IA: 5.97 m/s, 19,482 kWh, payback 35 years (24 mi)
- Appanoose County, IA: 5.93 m/s, 19,186 kWh, payback 36 years (24 mi)
- Scotland County, MO: 5.84 m/s, 18,521 kWh, payback 38 years (25 mi)
- Jefferson County, IA: 5.97 m/s, 19,482 kWh, payback 35 years (29 mi)
Sun versus wind in Davis County
Davis County gets 4.09 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,194 kWh a year; one kW of the turbine above makes 1,546. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.3 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.