Wind Turbine Payback in Sangamon County, IL
Wind turbine payback in Sangamon 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 Sangamon County, IL averages 5.95 m/s (13.3 mph). A 10 kW turbine there would make about 19,334 kWh a year, worth $3,718 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 Sangamon County
A home turbine is not worth buying for savings in Sangamon County unless your spot is far windier than the county average, 6.8 m/s at the hub against 5.95 m/s here. Per kW, solar panels would make about 1,200 kWh a year here against the turbine's 1,933, so get a solar quote first.
What would have to change
- Power would have to cost 26¢/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 5.95. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IL
Sangamon County is the 914th 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 Sangamon County
April is the strongest month here, at 6.97 m/s and about 2,207 kWh. July is the weakest, 4.49 m/s and 790 kWh, so the best month makes 2.8 times the worst. November to March brings in 51% of the year's output in Sangamon County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.59 m/s | 2,045 kWh | $393 |
| February | 6.54 m/s | 1,817 kWh | $349 |
| March | 6.65 m/s | 2,083 kWh | $401 |
| April | 6.97 m/s | 2,207 kWh | $424 |
| May | 6.00 m/s | 1,676 kWh | $322 |
| June | 5.24 m/s | 1,166 kWh | $224 |
| July | 4.49 m/s | 790 kWh | $152 |
| August | 4.53 m/s | 809 kWh | $156 |
| September | 5.13 m/s | 1,100 kWh | $212 |
| October | 6.21 m/s | 1,805 kWh | $347 |
| November | 6.64 m/s | 2,011 kWh | $387 |
| December | 6.44 m/s | 1,950 kWh | $375 |
What a taller tower would buy
Measured at 10 m the wind in Sangamon County averages 4.61 m/s; at 50 m it is 6.7 m/s. That gives a shear exponent of 0.232, typical of ordinary open country. Going from 20 m to 50 m takes output from 15,440 to 24,874 kWh a year, 61% 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 | 5.42 m/s | 15,440 kWh | 34 years |
| 30 m | 5.95 m/s | 19,343 kWh | 27 years |
| 40 m | 6.36 m/s | 22,388 kWh | 23 years |
| 50 m | 6.7 m/s | 24,874 kWh | 21 years |
Counties around Sangamon County
None of the 6 closest counties is windier than Sangamon County.
- Menard County, IL: 5.88 m/s, 18,816 kWh, payback 28 years (20 mi)
- Christian County, IL: 5.91 m/s, 19,038 kWh, payback 27 years (25 mi)
- Morgan County, IL: 5.84 m/s, 18,521 kWh, payback 28 years (29 mi)
- Logan County, IL: 5.95 m/s, 19,334 kWh, payback 27 years (30 mi)
- Cass County, IL: 5.88 m/s, 18,816 kWh, payback 28 years (34 mi)
- Mason County, IL: 5.88 m/s, 18,816 kWh, payback 28 years (36 mi)
Sun versus wind in Sangamon County
Sangamon County gets 4.11 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,200 kWh a year; one kW of the turbine above makes 1,933. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.6 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.