Wind Turbine Payback in Santa Clara County, CA
Wind turbine payback in Santa Clara 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 Santa Clara County, CA averages 3.46 m/s (7.7 mph). A 10 kW turbine there would make about 4,172 kWh a year, worth $1,359 at CA's 32.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 74 years, and the turbine is built to last about 20.
What to do in Santa Clara County
A home turbine is not worth buying for savings in Santa Clara County unless your spot is far windier than the county average, 5.4 m/s at the hub against 3.46 m/s here. Per kW, solar panels would make about 1,553 kWh a year here against the turbine's 417, so get a solar quote first.
What would have to change
- Power would have to cost 120¢/kWh, 3.7 times what CA pays now.
- Or the average wind at the hub would have to be 5.4 m/s instead of 3.46. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of CA
Santa Clara County is the 2,562nd 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 Santa Clara County
December is the strongest month here, at 3.80 m/s and about 477 kWh. September is the weakest, 3.01 m/s and 216 kWh, so the best month makes 2.2 times the worst. November to March brings in 47% of the year's output in Santa Clara County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.54 m/s | 381 kWh | $124 |
| February | 3.75 m/s | 412 kWh | $134 |
| March | 3.62 m/s | 408 kWh | $133 |
| April | 3.76 m/s | 448 kWh | $146 |
| May | 3.70 m/s | 440 kWh | $143 |
| June | 3.64 m/s | 404 kWh | $132 |
| July | 3.16 m/s | 262 kWh | $85 |
| August | 3.06 m/s | 236 kWh | $77 |
| September | 3.01 m/s | 216 kWh | $70 |
| October | 3.13 m/s | 255 kWh | $83 |
| November | 3.40 m/s | 324 kWh | $106 |
| December | 3.80 m/s | 477 kWh | $155 |
What a taller tower would buy
Measured at 10 m the wind in Santa Clara County averages 2.56 m/s; at 50 m it is 3.98 m/s. That gives a shear exponent of 0.274, typical of ordinary open country. Going from 20 m to 50 m takes output from 2,895 to 6,477 kWh a year, 124% 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 | 3.1 m/s | 2,895 kWh | over 100 years |
| 30 m | 3.46 m/s | 4,172 kWh | 74 years |
| 40 m | 3.74 m/s | 5,360 kWh | 57 years |
| 50 m | 3.98 m/s | 6,477 kWh | 47 years |
Counties around Santa Clara County
5 of the 6 closest counties are windier at turbine height; the windiest, San Mateo County, averages 5.02 m/s.
- Santa Cruz County, CA: 3.46 m/s, 4,172 kWh, payback 74 years (23 mi)
- Alameda County, CA: 4.17 m/s, 7,461 kWh, payback 41 years (32 mi)
- San Mateo County, CA: 5.02 m/s, 12,670 kWh, payback 24 years (40 mi)
- Stanislaus County, CA: 4.35 m/s, 8,460 kWh, payback 36 years (44 mi)
- Contra Costa County, CA: 4.85 m/s, 11,537 kWh, payback 27 years (50 mi)
- Merced County, CA: 4.5 m/s, 9,339 kWh, payback 33 years (53 mi)
Sun versus wind in Santa Clara County
Santa Clara County gets 5.32 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,553 kWh a year; one kW of the turbine above makes 417. Kilowatt for kilowatt, panels make 3.7 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.