Wind Turbine Payback in Carroll County, IL
Wind turbine payback in Carroll 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 Carroll County, IL averages 5.92 m/s (13.2 mph). A 10 kW turbine there would make about 19,112 kWh a year, worth $3,675 at IL's 19.23¢/kWh. Against an installed cost of about $100,000, that is a payback of 27 years, and the turbine is built to last about 20.
What to do in Carroll County
A home turbine is not worth buying for savings in Carroll County unless your spot is far windier than the county average, 6.8 m/s at the hub against 5.92 m/s here. Per kW, solar panels would make about 1,145 kWh a year here against the turbine's 1,911, so get a solar quote first.
What would have to change
- Power would have to cost 26¢/kWh, 1.4 times what IL pays now.
- Or the average wind at the hub would have to be 6.8 m/s instead of 5.92. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IL
Carroll County is the 959th 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 Carroll County
April is the strongest month here, at 6.85 m/s and about 2,136 kWh. August is the weakest, 4.59 m/s and 841 kWh, so the best month makes 2.5 times the worst. November to March brings in 49% of the year's output in Carroll County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.39 m/s | 1,919 kWh | $369 |
| February | 6.45 m/s | 1,769 kWh | $340 |
| March | 6.52 m/s | 2,003 kWh | $385 |
| April | 6.85 m/s | 2,136 kWh | $411 |
| May | 6.05 m/s | 1,706 kWh | $328 |
| June | 5.29 m/s | 1,193 kWh | $229 |
| July | 4.63 m/s | 860 kWh | $165 |
| August | 4.59 m/s | 841 kWh | $162 |
| September | 5.46 m/s | 1,292 kWh | $248 |
| October | 6.22 m/s | 1,813 kWh | $349 |
| November | 6.45 m/s | 1,895 kWh | $364 |
| December | 6.19 m/s | 1,791 kWh | $344 |
What a taller tower would buy
Measured at 10 m the wind in Carroll County averages 4.61 m/s; at 50 m it is 6.65 m/s. That gives a shear exponent of 0.228, typical of ordinary open country. Going from 20 m to 50 m takes output from 15,292 to 24,509 kWh a year, 60% 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 | 5.4 m/s | 15,292 kWh | 34 years |
| 30 m | 5.92 m/s | 19,104 kWh | 27 years |
| 40 m | 6.32 m/s | 22,078 kWh | 24 years |
| 50 m | 6.65 m/s | 24,509 kWh | 21 years |
Counties around Carroll County
5 of the 6 closest counties are windier at turbine height; the windiest, Stephenson County, averages 5.98 m/s.
- Whiteside County, IL: 5.92 m/s, 19,112 kWh, payback 27 years (22 mi)
- Stephenson County, IL: 5.98 m/s, 19,556 kWh, payback 27 years (23 mi)
- Jo Daviess County, IL: 5.96 m/s, 19,408 kWh, payback 27 years (25 mi)
- Ogle County, IL: 5.97 m/s, 19,482 kWh, payback 27 years (31 mi)
- Clinton County, IA: 5.95 m/s, 19,334 kWh, payback 36 years (34 mi)
- Jackson County, IA: 5.95 m/s, 19,334 kWh, payback 36 years (34 mi)
Sun versus wind in Carroll County
Carroll County gets 3.92 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,145 kWh a year; one kW of the turbine above makes 1,911. 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.