Wind Turbine Payback in St. Clair County, MO
Wind turbine payback in St. Clair 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. Clair County, MO averages 5.01 m/s (11.2 mph). A 10 kW turbine there would make about 12,602 kWh a year, worth $1,800 at MO's 14.28¢/kWh. Against an installed cost of about $100,000, that is a payback of 56 years, and the turbine is built to last about 20.
What to do in St. Clair County
A home turbine is not worth buying for savings in St. Clair County unless your spot is far windier than the county average, 8.2 m/s at the hub against 5.01 m/s here. Per kW, solar panels would make about 1,247 kWh a year here against the turbine's 1,260, so get a solar quote first.
What would have to change
- Power would have to cost 40¢/kWh, 2.8 times what MO pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 5.01. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MO
St. Clair County is the 1,449th 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. Clair County
March is the strongest month here, at 5.79 m/s and about 1,543 kWh. July is the weakest, 3.89 m/s and 512 kWh, so the best month makes 3.0 times the worst. November to March brings in 51% of the year's output in St. Clair County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.46 m/s | 1,340 kWh | $191 |
| February | 5.56 m/s | 1,263 kWh | $180 |
| March | 5.79 m/s | 1,543 kWh | $220 |
| April | 5.87 m/s | 1,541 kWh | $220 |
| May | 5.00 m/s | 1,067 kWh | $152 |
| June | 4.57 m/s | 803 kWh | $115 |
| July | 3.89 m/s | 512 kWh | $73 |
| August | 3.95 m/s | 537 kWh | $77 |
| September | 4.34 m/s | 690 kWh | $99 |
| October | 5.11 m/s | 1,127 kWh | $161 |
| November | 5.42 m/s | 1,271 kWh | $181 |
| December | 5.30 m/s | 1,240 kWh | $177 |
What a taller tower would buy
Measured at 10 m the wind in St. Clair County averages 3.68 m/s; at 50 m it is 5.79 m/s. That gives a shear exponent of 0.282, typical of ordinary open country. Going from 20 m to 50 m takes output from 9,169 to 18,153 kWh a year, 98% 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 | 4.47 m/s | 9,169 kWh | 76 years |
| 30 m | 5.01 m/s | 12,624 kWh | 56 years |
| 40 m | 5.44 m/s | 15,583 kWh | 45 years |
| 50 m | 5.79 m/s | 18,153 kWh | 39 years |
Counties around St. Clair County
4 of the 6 closest counties are windier at turbine height; the windiest, Bates County, averages 5.9 m/s.
- Cedar County, MO: 5.73 m/s, 17,712 kWh, payback 40 years (22 mi)
- Henry County, MO: 5.42 m/s, 15,462 kWh, payback 45 years (24 mi)
- Hickory County, MO: 3.84 m/s, 5,800 kWh, payback over 100 years (26 mi)
- Benton County, MO: 4.81 m/s, 11,276 kWh, payback 62 years (32 mi)
- Vernon County, MO: 5.81 m/s, 18,300 kWh, payback 38 years (34 mi)
- Bates County, MO: 5.9 m/s, 18,964 kWh, payback 37 years (34 mi)
Sun versus wind in St. Clair County
St. Clair County gets 4.27 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,247 kWh a year; one kW of the turbine above makes 1,260. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.0 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.