Wind Turbine Payback in Shelby County, IL
Wind turbine payback in Shelby 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 Shelby 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 Shelby County
A home turbine is not worth buying for savings in Shelby 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 1,188 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
Shelby 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 Shelby County
April is the strongest month here, at 7.03 m/s and about 2,240 kWh. July is the weakest, 4.43 m/s and 756 kWh, so the best month makes 3.0 times the worst. November to March brings in 52% of the year's output in Shelby County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.67 m/s | 2,091 kWh | $402 |
| February | 6.61 m/s | 1,859 kWh | $357 |
| March | 6.72 m/s | 2,124 kWh | $408 |
| April | 7.03 m/s | 2,240 kWh | $431 |
| May | 6.01 m/s | 1,678 kWh | $323 |
| June | 5.20 m/s | 1,142 kWh | $220 |
| July | 4.43 m/s | 756 kWh | $145 |
| August | 4.48 m/s | 783 kWh | $151 |
| September | 5.06 m/s | 1,062 kWh | $204 |
| October | 6.19 m/s | 1,796 kWh | $345 |
| November | 6.67 m/s | 2,029 kWh | $390 |
| December | 6.48 m/s | 1,975 kWh | $380 |
What a taller tower would buy
Measured at 10 m the wind in Shelby County averages 4.62 m/s; at 50 m it is 6.7 m/s. That gives a shear exponent of 0.231, typical of ordinary open country. Going from 20 m to 50 m takes output from 15,475 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 | 15,475 kWh | 34 years |
| 30 m | 5.95 m/s | 19,365 kWh | 27 years |
| 40 m | 6.36 m/s | 22,398 kWh | 23 years |
| 50 m | 6.7 m/s | 24,874 kWh | 21 years |
Counties around Shelby County
None of the 6 closest counties is windier than Shelby County.
- Moultrie County, IL: 5.95 m/s, 19,334 kWh, payback 27 years (20 mi)
- Effingham County, IL: 5.82 m/s, 18,374 kWh, payback 28 years (26 mi)
- Christian County, IL: 5.91 m/s, 19,038 kWh, payback 27 years (28 mi)
- Fayette County, IL: 5.82 m/s, 18,374 kWh, payback 28 years (29 mi)
- Cumberland County, IL: 5.91 m/s, 19,038 kWh, payback 27 years (31 mi)
- Coles County, IL: 5.91 m/s, 19,038 kWh, payback 27 years (32 mi)
Sun versus wind in Shelby County
Shelby County gets 4.07 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,188 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.