Wind Turbine Payback in San Mateo County, CA
Wind turbine payback in San Mateo 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 San Mateo County, CA averages 5.02 m/s (11.2 mph). A 10 kW turbine there would make about 12,670 kWh a year, worth $4,128 at CA's 32.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 24 years, and the turbine is built to last about 20.
What to do in San Mateo County
A home turbine is not worth buying for savings in San Mateo County unless your spot is far windier than the county average, 5.4 m/s at the hub against 5.02 m/s here. Per kW, solar panels would make about 1,384 kWh a year here against the turbine's 1,267, so get a solar quote first.
What would have to change
- Power would have to cost 39¢/kWh, 1.2 times what CA pays now.
- Or the average wind at the hub would have to be 5.4 m/s instead of 5.02. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of CA
San Mateo County is the 1,446th 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 San Mateo County
May is the strongest month here, at 5.57 m/s and about 1,407 kWh. September is the weakest, 4.30 m/s and 672 kWh, so the best month makes 2.1 times the worst. November to March brings in 45% of the year's output in San Mateo County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.07 m/s | 1,104 kWh | $360 |
| February | 5.49 m/s | 1,224 kWh | $399 |
| March | 5.36 m/s | 1,276 kWh | $416 |
| April | 5.56 m/s | 1,356 kWh | $442 |
| May | 5.57 m/s | 1,407 kWh | $458 |
| June | 5.49 m/s | 1,312 kWh | $427 |
| July | 4.64 m/s | 864 kWh | $281 |
| August | 4.42 m/s | 754 kWh | $246 |
| September | 4.30 m/s | 672 kWh | $219 |
| October | 4.32 m/s | 703 kWh | $229 |
| November | 4.61 m/s | 822 kWh | $268 |
| December | 5.45 m/s | 1,332 kWh | $434 |
What a taller tower would buy
Measured at 10 m the wind in San Mateo County averages 4.36 m/s; at 50 m it is 5.36 m/s. That gives a shear exponent of 0.128, typical of very open, smooth ground where height adds little. Going from 20 m to 50 m takes output from 10,997 to 15,034 kWh a year, 37% 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 | 4.77 m/s | 10,997 kWh | 28 years |
| 30 m | 5.02 m/s | 12,675 kWh | 24 years |
| 40 m | 5.21 m/s | 13,970 kWh | 22 years |
| 50 m | 5.36 m/s | 15,034 kWh | 20 years |
Counties around San Mateo County
1 of the 6 closest counties is windier at turbine height; the windiest, San Francisco County, averages 6.53 m/s.
- Alameda County, CA: 4.17 m/s, 7,461 kWh, payback 41 years (30 mi)
- Santa Cruz County, CA: 3.46 m/s, 4,172 kWh, payback 74 years (34 mi)
- Santa Clara County, CA: 3.46 m/s, 4,172 kWh, payback 74 years (40 mi)
- Contra Costa County, CA: 4.85 m/s, 11,537 kWh, payback 27 years (42 mi)
- San Francisco County, CA: 6.53 m/s, 23,628 kWh, payback 13 years (42 mi)
- Marin County, CA: 4.37 m/s, 8,575 kWh, payback 36 years (49 mi)
Sun versus wind in San Mateo County
San Mateo County gets 4.74 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,384 kWh a year; one kW of the turbine above makes 1,267. Kilowatt for kilowatt, panels make 1.1 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.