Wind Turbine Payback in St. Charles County, MO
Wind turbine payback in St. Charles 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 St. Charles County, MO averages 5.06 m/s (11.3 mph). A 10 kW turbine there would make about 12,941 kWh a year, worth $1,848 at MO's 14.28¢/kWh. Against an installed cost of about $100,000, that is a payback of 54 years, and the turbine is built to last about 20.
What to do in St. Charles County
A home turbine is not worth buying for savings in St. Charles County unless your spot is far windier than the county average, 8.2 m/s at the hub against 5.06 m/s here. Per kW, solar panels would make about 1,218 kWh a year here against the turbine's 1,294, so get a solar quote first.
What would have to change
- Power would have to cost 39¢/kWh, 2.7 times what MO pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 5.06. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MO
St. Charles County is the 1,422nd windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in MO is Atchison County at 6.17 m/s, payback 33 years.
Month by month in St. Charles County
March is the strongest month here, at 5.83 m/s and about 1,567 kWh. August is the weakest, 3.83 m/s and 487 kWh, so the best month makes 3.2 times the worst. November to March brings in 54% of the year's output in St. Charles County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.74 m/s | 1,513 kWh | $216 |
| February | 5.74 m/s | 1,362 kWh | $194 |
| March | 5.83 m/s | 1,567 kWh | $224 |
| April | 5.91 m/s | 1,564 kWh | $223 |
| May | 4.99 m/s | 1,061 kWh | $152 |
| June | 4.36 m/s | 699 kWh | $100 |
| July | 3.85 m/s | 498 kWh | $71 |
| August | 3.83 m/s | 487 kWh | $70 |
| September | 4.30 m/s | 671 kWh | $96 |
| October | 5.20 m/s | 1,183 kWh | $169 |
| November | 5.56 m/s | 1,354 kWh | $193 |
| December | 5.53 m/s | 1,383 kWh | $197 |
What a taller tower would buy
Measured at 10 m the wind in St. Charles County averages 3.77 m/s; at 50 m it is 5.81 m/s. That gives a shear exponent of 0.269, typical of ordinary open country. Going from 20 m to 50 m takes output from 9,585 to 18,300 kWh a year, 91% 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 | 4.54 m/s | 9,585 kWh | 73 years |
| 30 m | 5.06 m/s | 12,969 kWh | 54 years |
| 40 m | 5.47 m/s | 15,832 kWh | 44 years |
| 50 m | 5.81 m/s | 18,300 kWh | 38 years |
Counties around St. Charles County
None of the 6 closest counties is windier than St. Charles County.
- St. Louis County, MO: 4.11 m/s, 7,143 kWh, payback 98 years (16 mi)
- Lincoln County, MO: 4.55 m/s, 9,641 kWh, payback 73 years (25 mi)
- St. Louis city, MO: 5.05 m/s, 12,873 kWh, payback 54 years (25 mi)
- Warren County, MO: 4.55 m/s, 9,641 kWh, payback 73 years (26 mi)
- Calhoun County, IL: 5.06 m/s, 12,941 kWh, payback 40 years (26 mi)
- Jersey County, IL: 5.06 m/s, 12,941 kWh, payback 40 years (27 mi)
Sun versus wind in St. Charles County
St. Charles County gets 4.17 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,218 kWh a year; one kW of the turbine above makes 1,294. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.1 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.