Wind Turbine Payback in King County, TX
Wind turbine payback in King 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 King County, TX averages 6.14 m/s (13.7 mph). A 10 kW turbine there would make about 20,742 kWh a year, worth $3,325 at TX's 16.03¢/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 King County
A home turbine is not worth buying for savings in King County unless your spot is far windier than the county average, 7.6 m/s at the hub against 6.14 m/s here. Per kW, solar panels would make about 1,521 kWh a year here against the turbine's 2,074, so get a solar quote first.
What would have to change
- Power would have to cost 24¢/kWh, 1.5 times what TX pays now.
- Or the average wind at the hub would have to be 7.6 m/s instead of 6.14. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TX
King County is the 646th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in TX is Dallam County at 6.82 m/s, payback 24 years.
Month by month in King County
April is the strongest month here, at 7.10 m/s and about 2,280 kWh. August is the weakest, 5.26 m/s and 1,219 kWh, so the best month makes 1.9 times the worst. November to March brings in 44% of the year's output in King County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.14 m/s | 1,765 kWh | $283 |
| February | 6.30 m/s | 1,680 kWh | $269 |
| March | 6.62 m/s | 2,061 kWh | $330 |
| April | 7.10 m/s | 2,280 kWh | $365 |
| May | 6.48 m/s | 1,977 kWh | $317 |
| June | 6.24 m/s | 1,767 kWh | $283 |
| July | 5.52 m/s | 1,375 kWh | $220 |
| August | 5.26 m/s | 1,219 kWh | $195 |
| September | 5.44 m/s | 1,283 kWh | $206 |
| October | 6.14 m/s | 1,759 kWh | $282 |
| November | 6.35 m/s | 1,832 kWh | $294 |
| December | 6.11 m/s | 1,742 kWh | $279 |
What a taller tower would buy
Measured at 10 m the wind in King County averages 4.78 m/s; at 50 m it is 6.89 m/s. That gives a shear exponent of 0.227, typical of ordinary open country. Going from 20 m to 50 m takes output from 16,733 to 26,253 kWh a year, 57% 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 | 5.6 m/s | 16,733 kWh | 37 years |
| 30 m | 6.14 m/s | 20,710 kWh | 30 years |
| 40 m | 6.55 m/s | 23,773 kWh | 26 years |
| 50 m | 6.89 m/s | 26,253 kWh | 24 years |
Counties around King County
3 of the 6 closest counties are windier at turbine height; the windiest, Stonewall County, averages 6.23 m/s.
- Knox County, TX: 6.14 m/s, 20,742 kWh, payback 30 years (30 mi)
- Stonewall County, TX: 6.23 m/s, 21,410 kWh, payback 29 years (30 mi)
- Dickens County, TX: 6.23 m/s, 21,410 kWh, payback 29 years (31 mi)
- Cottle County, TX: 6.1 m/s, 20,446 kWh, payback 31 years (33 mi)
- Foard County, TX: 6.1 m/s, 20,446 kWh, payback 31 years (34 mi)
- Kent County, TX: 6.23 m/s, 21,410 kWh, payback 29 years (42 mi)
Sun versus wind in King County
King County gets 5.21 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,521 kWh a year; one kW of the turbine above makes 2,074. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.4 times. 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.