Wind Turbine Payback in De Witt County, IL
Wind turbine payback in De Witt 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 De Witt County, IL averages 6.04 m/s (13.5 mph). A 10 kW turbine there would make about 20,001 kWh a year, worth $3,846 at IL's 19.23¢/kWh. Against an installed cost of about $100,000, that is a payback of 26 years, and the turbine is built to last about 20.
What to do in De Witt County
A home turbine is not worth buying for savings in De Witt County unless your spot is far windier than the county average, 6.8 m/s at the hub against 6.04 m/s here. Per kW, solar panels would make about 1,174 kWh a year here against the turbine's 2,000, so get a solar quote first.
What would have to change
- Power would have to cost 25¢/kWh, 1.3 times what IL pays now.
- Or the average wind at the hub would have to be 6.8 m/s instead of 6.04. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IL
De Witt County is the 784th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in IL is Cook County at 6.73 m/s, payback 21 years.
Month by month in De Witt County
April is the strongest month here, at 7.10 m/s and about 2,281 kWh. July is the weakest, 4.55 m/s and 817 kWh, so the best month makes 2.8 times the worst. November to March brings in 51% of the year's output in De Witt County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.71 m/s | 2,117 kWh | $407 |
| February | 6.66 m/s | 1,887 kWh | $363 |
| March | 6.75 m/s | 2,145 kWh | $412 |
| April | 7.10 m/s | 2,281 kWh | $439 |
| May | 6.13 m/s | 1,755 kWh | $337 |
| June | 5.29 m/s | 1,197 kWh | $230 |
| July | 4.55 m/s | 817 kWh | $157 |
| August | 4.55 m/s | 821 kWh | $158 |
| September | 5.19 m/s | 1,135 kWh | $218 |
| October | 6.30 m/s | 1,861 kWh | $358 |
| November | 6.76 m/s | 2,081 kWh | $400 |
| December | 6.56 m/s | 2,023 kWh | $389 |
What a taller tower would buy
Measured at 10 m the wind in De Witt County averages 4.7 m/s; at 50 m it is 6.79 m/s. That gives a shear exponent of 0.229, typical of ordinary open country. Going from 20 m to 50 m takes output from 16,072 to 25,529 kWh a year, 59% 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 | 5.5 m/s | 16,072 kWh | 32 years |
| 30 m | 6.04 m/s | 20,004 kWh | 26 years |
| 40 m | 6.45 m/s | 23,051 kWh | 23 years |
| 50 m | 6.79 m/s | 25,529 kWh | 20 years |
Counties around De Witt County
1 of the 6 closest counties is windier at turbine height; the windiest, McLean County, averages 6.13 m/s.
- Piatt County, IL: 6.04 m/s, 20,001 kWh, payback 26 years (20 mi)
- McLean County, IL: 6.13 m/s, 20,668 kWh, payback 25 years (22 mi)
- Macon County, IL: 6.04 m/s, 20,001 kWh, payback 26 years (22 mi)
- Logan County, IL: 5.95 m/s, 19,334 kWh, payback 27 years (25 mi)
- Champaign County, IL: 6 m/s, 19,704 kWh, payback 26 years (37 mi)
- Tazewell County, IL: 6.02 m/s, 19,852 kWh, payback 26 years (39 mi)
Sun versus wind in De Witt County
De Witt County gets 4.02 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,174 kWh a year; one kW of the turbine above makes 2,000. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.7 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.