Wind Turbine Payback in Montgomery County, IL
Wind turbine payback in Montgomery 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 Montgomery County, IL averages 5.8 m/s (13 mph). A 10 kW turbine there would make about 18,226 kWh a year, worth $3,505 at IL's 19.23¢/kWh. Against an installed cost of about $100,000, that is a payback of 29 years, and the turbine is built to last about 20.
What to do in Montgomery County
A home turbine is not worth buying for savings in Montgomery County unless your spot is far windier than the county average, 6.8 m/s at the hub against 5.8 m/s here. Per kW, solar panels would make about 1,200 kWh a year here against the turbine's 1,823, so get a solar quote first.
What would have to change
- Power would have to cost 27¢/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 5.8. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IL
Montgomery County is the 1,064th 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 Montgomery County
April is the strongest month here, at 6.83 m/s and about 2,125 kWh. July is the weakest, 4.30 m/s and 694 kWh, so the best month makes 3.1 times the worst. November to March brings in 52% of the year's output in Montgomery County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.53 m/s | 2,009 kWh | $386 |
| February | 6.48 m/s | 1,784 kWh | $343 |
| March | 6.60 m/s | 2,053 kWh | $395 |
| April | 6.83 m/s | 2,125 kWh | $409 |
| May | 5.81 m/s | 1,557 kWh | $299 |
| June | 5.01 m/s | 1,035 kWh | $199 |
| July | 4.30 m/s | 694 kWh | $133 |
| August | 4.35 m/s | 720 kWh | $138 |
| September | 4.87 m/s | 957 kWh | $184 |
| October | 6.03 m/s | 1,691 kWh | $325 |
| November | 6.51 m/s | 1,928 kWh | $371 |
| December | 6.34 m/s | 1,886 kWh | $363 |
What a taller tower would buy
Measured at 10 m the wind in Montgomery County averages 4.47 m/s; at 50 m it is 6.54 m/s. That gives a shear exponent of 0.236, typical of ordinary open country. Going from 20 m to 50 m takes output from 14,384 to 23,702 kWh a year, 65% 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 | 5.27 m/s | 14,384 kWh | 36 years |
| 30 m | 5.8 m/s | 18,206 kWh | 29 years |
| 40 m | 6.2 m/s | 21,221 kWh | 25 years |
| 50 m | 6.54 m/s | 23,702 kWh | 22 years |
Counties around Montgomery County
4 of the 6 closest counties are windier at turbine height; the windiest, Sangamon County, averages 5.95 m/s.
- Bond County, IL: 5.8 m/s, 18,226 kWh, payback 29 years (24 mi)
- Macoupin County, IL: 5.84 m/s, 18,521 kWh, payback 28 years (24 mi)
- Christian County, IL: 5.91 m/s, 19,038 kWh, payback 27 years (24 mi)
- Fayette County, IL: 5.82 m/s, 18,374 kWh, payback 28 years (29 mi)
- Madison County, IL: 5.57 m/s, 16,544 kWh, payback 31 years (36 mi)
- Sangamon County, IL: 5.95 m/s, 19,334 kWh, payback 27 years (38 mi)
Sun versus wind in Montgomery County
Montgomery 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 1,823. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.5 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.