Wind Turbine Payback in Island County, WA
Wind turbine payback in Island 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 Island County, WA averages 2.56 m/s (5.7 mph). A 10 kW turbine there would make about 1,477 kWh a year, worth $213 at WA's 14.42¢/kWh. Against an installed cost of about $100,000, that is a payback of over 100 years, and the turbine is built to last about 20.
What to do in Island County
A home turbine is not worth buying for savings in Island County unless your spot is far windier than the county average, 8.1 m/s at the hub against 2.56 m/s here. Per kW, solar panels would make about 1,016 kWh a year here against the turbine's 148, so get a solar quote first.
What would have to change
- Power would have to cost 339¢/kWh, 23.5 times what WA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 2.56. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of WA
Island County is the 3,135th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in WA is Columbia County at 5.18 m/s, payback 50 years.
Month by month in Island County
December is the strongest month here, at 3.27 m/s and about 295 kWh. July is the weakest, 1.81 m/s and 27 kWh, so the best month makes 10.9 times the worst. November to March brings in 72% of the year's output in Island County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.18 m/s | 268 kWh | $39 |
| February | 2.90 m/s | 178 kWh | $26 |
| March | 3.03 m/s | 230 kWh | $33 |
| April | 2.61 m/s | 130 kWh | $19 |
| May | 2.09 m/s | 55 kWh | $8 |
| June | 1.93 m/s | 37 kWh | $5 |
| July | 1.81 m/s | 27 kWh | $4 |
| August | 1.83 m/s | 29 kWh | $4 |
| September | 2.14 m/s | 58 kWh | $8 |
| October | 2.66 m/s | 144 kWh | $21 |
| November | 3.20 m/s | 266 kWh | $38 |
| December | 3.27 m/s | 295 kWh | $43 |
What a taller tower would buy
Measured at 10 m the wind in Island County averages 1.76 m/s; at 50 m it is 3.04 m/s. That gives a shear exponent of 0.340, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 849 to 2,721 kWh a year, 220% 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 | 2.23 m/s | 849 kWh | over 100 years |
| 30 m | 2.56 m/s | 1,467 kWh | over 100 years |
| 40 m | 2.82 m/s | 2,093 kWh | over 100 years |
| 50 m | 3.04 m/s | 2,721 kWh | over 100 years |
Counties around Island County
4 of the 6 closest counties are windier at turbine height; the windiest, San Juan County, averages 3.83 m/s.
- San Juan County, WA: 3.83 m/s, 5,753 kWh, payback over 100 years (31 mi)
- Kitsap County, WA: 2.97 m/s, 2,513 kWh, payback over 100 years (36 mi)
- Snohomish County, WA: 2.49 m/s, 1,330 kWh, payback over 100 years (42 mi)
- Skagit County, WA: 2.34 m/s, 1,043 kWh, payback over 100 years (46 mi)
- Jefferson County, WA: 3.01 m/s, 2,631 kWh, payback over 100 years (47 mi)
- Clallam County, WA: 3.01 m/s, 2,631 kWh, payback over 100 years (56 mi)
Sun versus wind in Island County
Island County gets 3.48 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,016 kWh a year; one kW of the turbine above makes 148. Kilowatt for kilowatt, panels make 6.9 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.