Wind Turbine Payback in Randolph County, IL
Wind turbine payback in Randolph 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 Randolph County, IL averages 4.69 m/s (10.5 mph). A 10 kW turbine there would make about 10,508 kWh a year, worth $2,021 at IL's 19.23¢/kWh. Against an installed cost of about $100,000, that is a payback of 50 years, and the turbine is built to last about 20.
What to do in Randolph County
A home turbine is not worth buying for savings in Randolph County unless your spot is far windier than the county average, 6.8 m/s at the hub against 4.69 m/s here. Per kW, solar panels would make about 1,221 kWh a year here against the turbine's 1,051, so get a solar quote first.
What would have to change
- Power would have to cost 48¢/kWh, 2.5 times what IL pays now.
- Or the average wind at the hub would have to be 6.8 m/s instead of 4.69. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IL
Randolph County is the 1,626th 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 Randolph County
March is the strongest month here, at 5.43 m/s and about 1,321 kWh. July is the weakest, 3.55 m/s and 386 kWh, so the best month makes 3.4 times the worst. November to March brings in 55% of the year's output in Randolph County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.35 m/s | 1,269 kWh | $244 |
| February | 5.37 m/s | 1,161 kWh | $223 |
| March | 5.43 m/s | 1,321 kWh | $254 |
| April | 5.50 m/s | 1,319 kWh | $254 |
| May | 4.64 m/s | 868 kWh | $167 |
| June | 3.99 m/s | 537 kWh | $103 |
| July | 3.55 m/s | 386 kWh | $74 |
| August | 3.58 m/s | 395 kWh | $76 |
| September | 3.96 m/s | 523 kWh | $101 |
| October | 4.76 m/s | 932 kWh | $179 |
| November | 5.15 m/s | 1,115 kWh | $214 |
| December | 5.12 m/s | 1,137 kWh | $219 |
What a taller tower would buy
Measured at 10 m the wind in Randolph County averages 3.38 m/s; at 50 m it is 5.47 m/s. That gives a shear exponent of 0.299, typical of ordinary open country. Going from 20 m to 50 m takes output from 7,403 to 15,821 kWh a year, 114% 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 | 4.16 m/s | 7,403 kWh | 70 years |
| 30 m | 4.7 m/s | 10,541 kWh | 49 years |
| 40 m | 5.12 m/s | 13,332 kWh | 39 years |
| 50 m | 5.47 m/s | 15,821 kWh | 33 years |
Counties around Randolph County
4 of the 6 closest counties are windier at turbine height; the windiest, Washington County, averages 5.65 m/s.
- Ste. Genevieve County, MO: 4.69 m/s, 10,508 kWh, payback 67 years (22 mi)
- Perry County, MO: 4.46 m/s, 9,100 kWh, payback 77 years (24 mi)
- Perry County, IL: 5.34 m/s, 14,892 kWh, payback 35 years (25 mi)
- Monroe County, IL: 5.05 m/s, 12,873 kWh, payback 40 years (25 mi)
- St. Clair County, IL: 5.05 m/s, 12,873 kWh, payback 40 years (29 mi)
- Washington County, IL: 5.65 m/s, 17,126 kWh, payback 30 years (30 mi)
Sun versus wind in Randolph County
Randolph County gets 4.18 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,221 kWh a year; one kW of the turbine above makes 1,051. Kilowatt for kilowatt, panels make 1.2 times as much here as the turbine. 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.