Wind Turbine Payback in Kauai County, HI
Wind turbine payback in Kauai County
Yes. A small turbine pays for itself here.
At 30 m, the height a home turbine tower usually reaches, the wind in Kauai County, HI averages 6.64 m/s (14.9 mph). A 10 kW turbine there would make about 24,436 kWh a year, worth $11,341 at HI's 46.41¢/kWh. Against an installed cost of about $100,000, that is a payback of 9 years, and the turbine is built to last about 20.
What to do in Kauai County
The numbers work, so the next step is proof. Before you buy, get a site assessment that logs wind at your actual tower spot for a few months, and check your county's zoning for tower height limits. If the logger reads below 4.7 m/s, walk away.
What would have to change
- Power already costs enough here: break-even is 20¢/kWh and HI pays 46.41¢.
- The wind clears the break-even speed of 4.7 m/s at today's price.
Against the rest of HI
Kauai County is the 97th 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 Kauai County
July is the strongest month here, at 7.29 m/s and about 2,473 kWh. May is the weakest, 5.98 m/s and 1,662 kWh, so the best month makes 1.5 times the worst. November to March brings in 41% of the year's output in Kauai County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.20 m/s | 1,802 kWh | $836 |
| February | 6.62 m/s | 1,863 kWh | $865 |
| March | 6.75 m/s | 2,146 kWh | $996 |
| April | 6.85 m/s | 2,134 kWh | $990 |
| May | 5.98 m/s | 1,662 kWh | $771 |
| June | 7.02 m/s | 2,237 kWh | $1,038 |
| July | 7.29 m/s | 2,473 kWh | $1,148 |
| August | 7.08 m/s | 2,347 kWh | $1,089 |
| September | 6.42 m/s | 1,873 kWh | $869 |
| October | 6.09 m/s | 1,729 kWh | $802 |
| November | 6.73 m/s | 2,060 kWh | $956 |
| December | 6.66 m/s | 2,086 kWh | $968 |
What a taller tower would buy
Measured at 10 m the wind in Kauai County averages 6.15 m/s; at 50 m it is 6.88 m/s. That gives a shear exponent of 0.070, typical of very open, smooth ground where height adds little. Going from 20 m to 50 m takes output from 23,057 to 26,181 kWh a year, 14% more, before counting the extra cost of the taller tower.
| Hub height | Average wind | Output | Payback |
|---|---|---|---|
| 20 m | 6.45 m/s | 23,057 kWh | 9 years |
| 30 m | 6.64 m/s | 24,423 kWh | 9 years |
| 40 m | 6.77 m/s | 25,409 kWh | 9 years |
| 50 m | 6.88 m/s | 26,181 kWh | 8 years |
Counties around Kauai County
3 of the 6 closest counties are windier at turbine height; the windiest, Aleutians West Census Area, averages 9.35 m/s.
- Honolulu County, HI: 6.85 m/s, 25,964 kWh, payback 8 years (104 mi)
- Kalawao County, HI: 6.46 m/s, 23,112 kWh, payback 9 years (184 mi)
- Maui County, HI: 6.46 m/s, 23,112 kWh, payback 9 years (215 mi)
- Hawaii County, HI: 3.43 m/s, 4,056 kWh, payback 53 years (319 mi)
- Aleutians East Borough, AK: 7.73 m/s, 32,079 kWh, payback 11 years (2299 mi)
- Aleutians West Census Area, AK: 9.35 m/s, 41,487 kWh, payback 9 years (2344 mi)
Sun versus wind in Kauai County
Kauai County gets 5.61 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,638 kWh a year; one kW of the turbine above makes 2,444. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.5 times. Panel output assumes an 80% system performance ratio.
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.