Wind Turbine Payback in Hawaii County, HI
Wind turbine payback in Hawaii 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 Hawaii County, HI averages 3.43 m/s (7.7 mph). A 10 kW turbine there would make about 4,056 kWh a year, worth $1,882 at HI's 46.41¢/kWh. Against an installed cost of about $100,000, that is a payback of 53 years, and the turbine is built to last about 20.
What to do in Hawaii County
A home turbine is not worth buying for savings in Hawaii County unless your spot is far windier than the county average, 4.7 m/s at the hub against 3.43 m/s here. Per kW, solar panels would make about 1,542 kWh a year here against the turbine's 406, so get a solar quote first.
What would have to change
- Power would have to cost 123¢/kWh, 2.7 times what HI pays now.
- Or the average wind at the hub would have to be 4.7 m/s instead of 3.43. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of HI
Hawaii County is the 2,587th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in HI is Honolulu County at 6.85 m/s, payback 8 years.
Month by month in Hawaii County
December is the strongest month here, at 4.19 m/s and about 641 kWh. September is the weakest, 2.89 m/s and 188 kWh, so the best month makes 3.4 times the worst. November to March brings in 54% of the year's output in Hawaii County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.60 m/s | 403 kWh | $187 |
| February | 3.70 m/s | 395 kWh | $183 |
| March | 3.52 m/s | 374 kWh | $174 |
| April | 3.59 m/s | 387 kWh | $180 |
| May | 2.95 m/s | 208 kWh | $97 |
| June | 3.23 m/s | 275 kWh | $128 |
| July | 3.31 m/s | 306 kWh | $142 |
| August | 3.23 m/s | 284 kWh | $132 |
| September | 2.89 m/s | 188 kWh | $87 |
| October | 3.20 m/s | 273 kWh | $127 |
| November | 3.75 m/s | 443 kWh | $206 |
| December | 4.19 m/s | 641 kWh | $297 |
What a taller tower would buy
Measured at 10 m the wind in Hawaii County averages 2.89 m/s; at 50 m it is 3.71 m/s. That gives a shear exponent of 0.155, typical of very open, smooth ground where height adds little. Going from 20 m to 50 m takes output from 3,295 to 5,209 kWh a year, 58% 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 | 3.22 m/s | 3,295 kWh | 65 years |
| 30 m | 3.43 m/s | 4,047 kWh | 53 years |
| 40 m | 3.58 m/s | 4,669 kWh | 46 years |
| 50 m | 3.71 m/s | 5,209 kWh | 41 years |
Counties around Hawaii County
6 of the 6 closest counties are windier at turbine height; the windiest, Honolulu County, averages 6.85 m/s.
- Maui County, HI: 6.46 m/s, 23,112 kWh, payback 9 years (112 mi)
- Kalawao County, HI: 6.46 m/s, 23,112 kWh, payback 9 years (147 mi)
- Honolulu County, HI: 6.85 m/s, 25,964 kWh, payback 8 years (217 mi)
- Kauai County, HI: 6.64 m/s, 24,436 kWh, payback 9 years (319 mi)
- San Francisco County, CA: 6.53 m/s, 23,628 kWh, payback 13 years (2315 mi)
- Marin County, CA: 4.37 m/s, 8,575 kWh, payback 36 years (2338 mi)
Sun versus wind in Hawaii County
Hawaii County gets 5.28 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,542 kWh a year; one kW of the turbine above makes 406. Kilowatt for kilowatt, panels make 3.8 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.