Wind Turbine Payback in DeKalb County, IL
Wind turbine payback in DeKalb 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 DeKalb County, IL averages 6.01 m/s (13.4 mph). A 10 kW turbine there would make about 19,778 kWh a year, worth $3,803 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 DeKalb County
A home turbine is not worth buying for savings in DeKalb County unless your spot is far windier than the county average, 6.8 m/s at the hub against 6.01 m/s here. Per kW, solar panels would make about 1,139 kWh a year here against the turbine's 1,978, 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 6.01. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IL
DeKalb County is the 826th 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 DeKalb County
April is the strongest month here, at 6.92 m/s and about 2,177 kWh. August is the weakest, 4.58 m/s and 834 kWh, so the best month makes 2.6 times the worst. November to March brings in 50% of the year's output in DeKalb County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.63 m/s | 2,068 kWh | $398 |
| February | 6.66 m/s | 1,883 kWh | $362 |
| March | 6.61 m/s | 2,057 kWh | $396 |
| April | 6.92 m/s | 2,177 kWh | $419 |
| May | 6.11 m/s | 1,744 kWh | $335 |
| June | 5.30 m/s | 1,201 kWh | $231 |
| July | 4.69 m/s | 891 kWh | $171 |
| August | 4.58 m/s | 834 kWh | $160 |
| September | 5.44 m/s | 1,285 kWh | $247 |
| October | 6.31 m/s | 1,868 kWh | $359 |
| November | 6.59 m/s | 1,980 kWh | $381 |
| December | 6.41 m/s | 1,929 kWh | $371 |
What a taller tower would buy
Measured at 10 m the wind in DeKalb County averages 4.69 m/s; at 50 m it is 6.75 m/s. That gives a shear exponent of 0.226, typical of ordinary open country. Going from 20 m to 50 m takes output from 15,946 to 25,239 kWh a year, 58% 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 | 5.49 m/s | 15,946 kWh | 33 years |
| 30 m | 6.01 m/s | 19,808 kWh | 26 years |
| 40 m | 6.42 m/s | 22,802 kWh | 23 years |
| 50 m | 6.75 m/s | 25,239 kWh | 21 years |
Counties around DeKalb County
3 of the 6 closest counties are windier at turbine height; the windiest, Kane County, averages 6.12 m/s.
- Kane County, IL: 6.12 m/s, 20,594 kWh, payback 25 years (18 mi)
- Kendall County, IL: 5.98 m/s, 19,556 kWh, payback 27 years (27 mi)
- Lee County, IL: 5.98 m/s, 19,556 kWh, payback 27 years (29 mi)
- Boone County, IL: 6.05 m/s, 20,075 kWh, payback 26 years (29 mi)
- Ogle County, IL: 5.97 m/s, 19,482 kWh, payback 27 years (30 mi)
- McHenry County, IL: 6.05 m/s, 20,075 kWh, payback 26 years (34 mi)
Sun versus wind in DeKalb County
DeKalb County gets 3.9 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,139 kWh a year; one kW of the turbine above makes 1,978. 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.