Wind Turbine Payback in Grand Isle County, VT
Wind turbine payback in Grand Isle 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 Grand Isle County, VT averages 3.97 m/s (8.9 mph). A 10 kW turbine there would make about 6,428 kWh a year, worth $1,538 at VT's 23.93¢/kWh. Against an installed cost of about $100,000, that is a payback of 65 years, and the turbine is built to last about 20.
What to do in Grand Isle County
A home turbine is not worth buying for savings in Grand Isle County unless your spot is far windier than the county average, 6.2 m/s at the hub against 3.97 m/s here. Per kW, solar panels would make about 1,031 kWh a year here against the turbine's 643, so get a solar quote first.
What would have to change
- Power would have to cost 78¢/kWh, 3.3 times what VT pays now.
- Or the average wind at the hub would have to be 6.2 m/s instead of 3.97. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of VT
Grand Isle County is the 2,080th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in VT is Franklin County at 3.97 m/s, payback 65 years.
Month by month in Grand Isle County
March is the strongest month here, at 4.73 m/s and about 916 kWh. August is the weakest, 3.23 m/s and 284 kWh, so the best month makes 3.2 times the worst. November to March brings in 57% of the year's output in Grand Isle County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.52 m/s | 806 kWh | $193 |
| February | 4.80 m/s | 860 kWh | $206 |
| March | 4.73 m/s | 916 kWh | $219 |
| April | 4.43 m/s | 735 kWh | $176 |
| May | 3.77 m/s | 464 kWh | $111 |
| June | 3.37 m/s | 316 kWh | $76 |
| July | 3.25 m/s | 289 kWh | $69 |
| August | 3.23 m/s | 284 kWh | $68 |
| September | 3.44 m/s | 337 kWh | $81 |
| October | 3.82 m/s | 483 kWh | $116 |
| November | 4.08 m/s | 576 kWh | $138 |
| December | 4.17 m/s | 632 kWh | $151 |
What a taller tower would buy
Measured at 10 m the wind in Grand Isle County averages 2.68 m/s; at 50 m it is 4.76 m/s. That gives a shear exponent of 0.357, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 4,063 to 10,954 kWh a year, 170% 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 | 3.43 m/s | 4,063 kWh | over 100 years |
| 30 m | 3.97 m/s | 6,410 kWh | 65 years |
| 40 m | 4.4 m/s | 8,722 kWh | 48 years |
| 50 m | 4.76 m/s | 10,954 kWh | 38 years |
Counties around Grand Isle County
1 of the 6 closest counties is windier at turbine height; the windiest, Clinton County, averages 4.11 m/s.
- Franklin County, VT: 3.97 m/s, 6,428 kWh, payback 65 years (20 mi)
- Clinton County, NY: 4.11 m/s, 7,143 kWh, payback 48 years (20 mi)
- Chittenden County, VT: 3.82 m/s, 5,707 kWh, payback 73 years (26 mi)
- Lamoille County, VT: 3.55 m/s, 4,530 kWh, payback 92 years (35 mi)
- Washington County, VT: 3.55 m/s, 4,530 kWh, payback 92 years (50 mi)
- Orleans County, VT: 3.77 m/s, 5,477 kWh, payback 76 years (51 mi)
Sun versus wind in Grand Isle County
Grand Isle County gets 3.53 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,031 kWh a year; one kW of the turbine above makes 643. Kilowatt for kilowatt, panels make 1.6 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.