Wind Turbine Payback in San Joaquin County, CA
Wind turbine payback in San Joaquin 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 Joaquin County, CA averages 4.09 m/s (9.1 mph). A 10 kW turbine there would make about 7,038 kWh a year, worth $2,293 at CA's 32.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 44 years, and the turbine is built to last about 20.
What to do in San Joaquin County
A home turbine is not worth buying for savings in San Joaquin County unless your spot is far windier than the county average, 5.4 m/s at the hub against 4.09 m/s here. Per kW, solar panels would make about 1,553 kWh a year here against the turbine's 704, so get a solar quote first.
What would have to change
- Power would have to cost 71¢/kWh, 2.2 times what CA pays now.
- Or the average wind at the hub would have to be 5.4 m/s instead of 4.09. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of CA
San Joaquin County is the 2,005th 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 Joaquin County
June is the strongest month here, at 4.69 m/s and about 862 kWh. November is the weakest, 3.46 m/s and 344 kWh, so the best month makes 2.5 times the worst. November to March brings in 34% of the year's output in San Joaquin County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.54 m/s | 383 kWh | $125 |
| February | 4.09 m/s | 541 kWh | $176 |
| March | 4.06 m/s | 583 kWh | $190 |
| April | 4.39 m/s | 714 kWh | $233 |
| May | 4.55 m/s | 820 kWh | $267 |
| June | 4.69 m/s | 862 kWh | $281 |
| July | 4.51 m/s | 797 kWh | $260 |
| August | 4.26 m/s | 673 kWh | $219 |
| September | 3.91 m/s | 506 kWh | $165 |
| October | 3.65 m/s | 421 kWh | $137 |
| November | 3.46 m/s | 344 kWh | $112 |
| December | 4.04 m/s | 576 kWh | $188 |
What a taller tower would buy
Measured at 10 m the wind in San Joaquin County averages 3.26 m/s; at 50 m it is 4.55 m/s. That gives a shear exponent of 0.207, typical of ordinary open country. Going from 20 m to 50 m takes output from 5,449 to 9,641 kWh a year, 77% 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 | 3.76 m/s | 5,449 kWh | 56 years |
| 30 m | 4.09 m/s | 7,056 kWh | 44 years |
| 40 m | 4.34 m/s | 8,429 kWh | 36 years |
| 50 m | 4.55 m/s | 9,641 kWh | 32 years |
Counties around San Joaquin County
4 of the 6 closest counties are windier at turbine height; the windiest, Contra Costa County, averages 4.85 m/s.
- Stanislaus County, CA: 4.35 m/s, 8,460 kWh, payback 36 years (30 mi)
- Sacramento County, CA: 3.82 m/s, 5,707 kWh, payback 54 years (36 mi)
- Contra Costa County, CA: 4.85 m/s, 11,537 kWh, payback 27 years (37 mi)
- Alameda County, CA: 4.17 m/s, 7,461 kWh, payback 41 years (40 mi)
- Calaveras County, CA: 3.22 m/s, 3,299 kWh, payback 93 years (43 mi)
- Solano County, CA: 4.42 m/s, 8,865 kWh, payback 35 years (43 mi)
Sun versus wind in San Joaquin County
San Joaquin 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 704. Kilowatt for kilowatt, panels make 2.2 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.