Wind Turbine Payback in Mariposa County, CA
Wind turbine payback in Mariposa 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 Mariposa County, CA averages 3.18 m/s (7.1 mph). A 10 kW turbine there would make about 3,165 kWh a year, worth $1,031 at CA's 32.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 97 years, and the turbine is built to last about 20.
What to do in Mariposa County
A home turbine is not worth buying for savings in Mariposa County unless your spot is far windier than the county average, 5.4 m/s at the hub against 3.18 m/s here. Per kW, solar panels would make about 1,556 kWh a year here against the turbine's 317, so get a solar quote first.
What would have to change
- Power would have to cost 158¢/kWh, 4.8 times what CA pays now.
- Or the average wind at the hub would have to be 5.4 m/s instead of 3.18. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of CA
Mariposa County is the 2,904th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in CA is San Francisco County at 6.53 m/s, payback 13 years.
Month by month in Mariposa County
January is the strongest month here, at 3.60 m/s and about 401 kWh. August is the weakest, 2.73 m/s and 158 kWh, so the best month makes 2.5 times the worst. November to March brings in 52% of the year's output in Mariposa County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.60 m/s | 401 kWh | $131 |
| February | 3.54 m/s | 345 kWh | $112 |
| March | 3.30 m/s | 305 kWh | $99 |
| April | 3.18 m/s | 260 kWh | $85 |
| May | 3.09 m/s | 244 kWh | $79 |
| June | 3.08 m/s | 234 kWh | $76 |
| July | 2.83 m/s | 181 kWh | $59 |
| August | 2.73 m/s | 158 kWh | $51 |
| September | 2.96 m/s | 203 kWh | $66 |
| October | 3.14 m/s | 258 kWh | $84 |
| November | 3.20 m/s | 267 kWh | $87 |
| December | 3.52 m/s | 376 kWh | $123 |
What a taller tower would buy
Measured at 10 m the wind in Mariposa County averages 2.46 m/s; at 50 m it is 3.58 m/s. That gives a shear exponent of 0.233, typical of ordinary open country. Going from 20 m to 50 m takes output from 2,292 to 4,653 kWh a year, 103% 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 | 2.89 m/s | 2,292 kWh | over 100 years |
| 30 m | 3.18 m/s | 3,159 kWh | 97 years |
| 40 m | 3.4 m/s | 3,937 kWh | 78 years |
| 50 m | 3.58 m/s | 4,653 kWh | 66 years |
Counties around Mariposa County
5 of the 6 closest counties are windier at turbine height; the windiest, Merced County, averages 4.5 m/s.
- Madera County, CA: 3.56 m/s, 4,570 kWh, payback 67 years (27 mi)
- Tuolumne County, CA: 3.32 m/s, 3,648 kWh, payback 84 years (31 mi)
- Merced County, CA: 4.5 m/s, 9,339 kWh, payback 33 years (52 mi)
- Calaveras County, CA: 3.22 m/s, 3,299 kWh, payback 93 years (55 mi)
- Fresno County, CA: 2.88 m/s, 2,259 kWh, payback over 100 years (58 mi)
- Stanislaus County, CA: 4.35 m/s, 8,460 kWh, payback 36 years (60 mi)
Sun versus wind in Mariposa County
Mariposa County gets 5.33 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,556 kWh a year; one kW of the turbine above makes 317. Kilowatt for kilowatt, panels make 4.9 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.