Wind Turbine Payback in St. Clair County, MI
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, MI averages 6.42 m/s (14.4 mph). A 10 kW turbine there would make about 22,817 kWh a year, worth $4,958 at MI's 21.73¢/kWh. Against an installed cost of about $100,000, that is a payback of 20 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, 6.4 m/s at the hub against 6.42 m/s here. Per kW, solar panels would make about 1,104 kWh a year here against the turbine's 2,282, so get a solar quote first.
What would have to change
- Power would have to cost 22¢/kWh, 1.0 times what MI pays now.
- Or the average wind at the hub would have to be 6.4 m/s instead of 6.42. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MI
St. Clair County is the 301st windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in MI is Keweenaw County at 7.4 m/s, payback 15 years.
Month by month in St. Clair County
January is the strongest month here, at 7.43 m/s and about 2,551 kWh. July is the weakest, 4.95 m/s and 1,038 kWh, so the best month makes 2.5 times the worst. November to March brings in 52% of the year's output in St. Clair County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.43 m/s | 2,551 kWh | $554 |
| February | 7.25 m/s | 2,208 kWh | $480 |
| March | 6.90 m/s | 2,238 kWh | $486 |
| April | 7.12 m/s | 2,293 kWh | $498 |
| May | 6.04 m/s | 1,697 kWh | $369 |
| June | 5.43 m/s | 1,278 kWh | $278 |
| July | 4.95 m/s | 1,038 kWh | $226 |
| August | 5.01 m/s | 1,069 kWh | $232 |
| September | 5.66 m/s | 1,413 kWh | $307 |
| October | 6.85 m/s | 2,205 kWh | $479 |
| November | 7.23 m/s | 2,356 kWh | $512 |
| December | 7.30 m/s | 2,477 kWh | $538 |
What a taller tower would buy
Measured at 10 m the wind in St. Clair County averages 5.15 m/s; at 50 m it is 7.12 m/s. That gives a shear exponent of 0.201, typical of ordinary open country. Going from 20 m to 50 m takes output from 19,129 to 27,897 kWh a year, 46% 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 | 5.92 m/s | 19,129 kWh | 24 years |
| 30 m | 6.43 m/s | 22,855 kWh | 20 years |
| 40 m | 6.81 m/s | 25,658 kWh | 18 years |
| 50 m | 7.12 m/s | 27,897 kWh | 17 years |
Counties around St. Clair County
1 of the 6 closest counties is windier at turbine height; the windiest, Sanilac County, averages 7.01 m/s.
- Macomb County, MI: 6.17 m/s, 20,965 kWh, payback 22 years (22 mi)
- Lapeer County, MI: 6.23 m/s, 21,410 kWh, payback 22 years (30 mi)
- Sanilac County, MI: 7.01 m/s, 27,114 kWh, payback 17 years (36 mi)
- Oakland County, MI: 6.17 m/s, 20,965 kWh, payback 22 years (41 mi)
- Genesee County, MI: 6.13 m/s, 20,668 kWh, payback 22 years (53 mi)
- Wayne County, MI: 6.17 m/s, 20,965 kWh, payback 22 years (54 mi)
Sun versus wind in St. Clair County
St. Clair County gets 3.78 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,104 kWh a year; one kW of the turbine above makes 2,282. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 2.1 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.