Wind Turbine Payback in Sonoma County, CA
Wind turbine payback in Sonoma 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 Sonoma County, CA averages 4.66 m/s (10.4 mph). A 10 kW turbine there would make about 10,320 kWh a year, worth $3,362 at CA's 32.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 30 years, and the turbine is built to last about 20.
What to do in Sonoma County
A home turbine is not worth buying for savings in Sonoma County unless your spot is far windier than the county average, 5.4 m/s at the hub against 4.66 m/s here. Per kW, solar panels would make about 1,501 kWh a year here against the turbine's 1,032, so get a solar quote first.
What would have to change
- Power would have to cost 48¢/kWh, 1.5 times what CA pays now.
- Or the average wind at the hub would have to be 5.4 m/s instead of 4.66. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of CA
Sonoma County is the 1,645th 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 Sonoma County
June is the strongest month here, at 5.55 m/s and about 1,349 kWh. November is the weakest, 4.19 m/s and 621 kWh, so the best month makes 2.2 times the worst. November to March brings in 37% of the year's output in Sonoma County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.32 m/s | 705 kWh | $230 |
| February | 4.69 m/s | 807 kWh | $263 |
| March | 4.71 m/s | 903 kWh | $294 |
| April | 5.01 m/s | 1,038 kWh | $338 |
| May | 5.29 m/s | 1,236 kWh | $403 |
| June | 5.55 m/s | 1,349 kWh | $440 |
| July | 4.65 m/s | 869 kWh | $283 |
| August | 4.43 m/s | 758 kWh | $247 |
| September | 4.39 m/s | 712 kWh | $232 |
| October | 4.20 m/s | 646 kWh | $210 |
| November | 4.19 m/s | 621 kWh | $202 |
| December | 4.60 m/s | 845 kWh | $275 |
What a taller tower would buy
Measured at 10 m the wind in Sonoma County averages 3.69 m/s; at 50 m it is 5.2 m/s. That gives a shear exponent of 0.213, typical of ordinary open country. Going from 20 m to 50 m takes output from 8,053 to 13,907 kWh a year, 73% 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 | 4.28 m/s | 8,053 kWh | 38 years |
| 30 m | 4.66 m/s | 10,344 kWh | 30 years |
| 40 m | 4.96 m/s | 12,257 kWh | 25 years |
| 50 m | 5.2 m/s | 13,907 kWh | 22 years |
Counties around Sonoma County
1 of the 6 closest counties is windier at turbine height; the windiest, San Francisco County, averages 6.53 m/s.
- Napa County, CA: 3.97 m/s, 6,428 kWh, payback 48 years (32 mi)
- Marin County, CA: 4.37 m/s, 8,575 kWh, payback 36 years (34 mi)
- Lake County, CA: 3.92 m/s, 6,182 kWh, payback 50 years (41 mi)
- San Francisco County, CA: 6.53 m/s, 23,628 kWh, payback 13 years (55 mi)
- Yolo County, CA: 4.42 m/s, 8,865 kWh, payback 35 years (56 mi)
- Solano County, CA: 4.42 m/s, 8,865 kWh, payback 35 years (56 mi)
Sun versus wind in Sonoma County
Sonoma County gets 5.14 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,501 kWh a year; one kW of the turbine above makes 1,032. Kilowatt for kilowatt, panels make 1.5 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.