Wind Turbine Payback in Rockbridge County, VA
Wind turbine payback in Rockbridge 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 Rockbridge County, VA averages 3.41 m/s (7.6 mph). A 10 kW turbine there would make about 3,980 kWh a year, worth $675 at VA's 16.95¢/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 Rockbridge County
A home turbine is not worth buying for savings in Rockbridge County unless your spot is far windier than the county average, 7.3 m/s at the hub against 3.41 m/s here. Per kW, solar panels would make about 1,232 kWh a year here against the turbine's 398, so get a solar quote first.
What would have to change
- Power would have to cost 126¢/kWh, 7.4 times what VA pays now.
- Or the average wind at the hub would have to be 7.3 m/s instead of 3.41. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of VA
Rockbridge County is the 2,607th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in VA is Northampton County at 7.01 m/s, payback 22 years.
Month by month in Rockbridge County
January is the strongest month here, at 4.10 m/s and about 604 kWh. August is the weakest, 2.51 m/s and 117 kWh, so the best month makes 5.2 times the worst. November to March brings in 61% of the year's output in Rockbridge County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.10 m/s | 604 kWh | $102 |
| February | 4.20 m/s | 585 kWh | $99 |
| March | 4.05 m/s | 579 kWh | $98 |
| April | 3.93 m/s | 510 kWh | $86 |
| May | 3.19 m/s | 270 kWh | $46 |
| June | 2.89 m/s | 189 kWh | $32 |
| July | 2.65 m/s | 142 kWh | $24 |
| August | 2.51 m/s | 117 kWh | $20 |
| September | 2.80 m/s | 169 kWh | $29 |
| October | 3.29 m/s | 301 kWh | $51 |
| November | 3.58 m/s | 381 kWh | $65 |
| December | 3.74 m/s | 453 kWh | $77 |
What a taller tower would buy
Measured at 10 m the wind in Rockbridge County averages 2.18 m/s; at 50 m it is 4.19 m/s. That gives a shear exponent of 0.406, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 2,282 to 7,569 kWh a year, 232% 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 | 2.89 m/s | 2,282 kWh | over 100 years |
| 30 m | 3.41 m/s | 3,962 kWh | over 100 years |
| 40 m | 3.83 m/s | 5,740 kWh | over 100 years |
| 50 m | 4.19 m/s | 7,569 kWh | 78 years |
Counties around Rockbridge County
None of the 6 closest counties is windier than Rockbridge County.
- Lexington city, VA: 3.41 m/s, 3,980 kWh, payback over 100 years (2 mi)
- Buena Vista city, VA: 3.02 m/s, 2,661 kWh, payback over 100 years (8 mi)
- Amherst County, VA: 3.02 m/s, 2,661 kWh, payback over 100 years (20 mi)
- Bath County, VA: 3.37 m/s, 3,830 kWh, payback over 100 years (23 mi)
- Botetourt County, VA: 3.19 m/s, 3,198 kWh, payback over 100 years (26 mi)
- Covington city, VA: 3.37 m/s, 3,830 kWh, payback over 100 years (29 mi)
Sun versus wind in Rockbridge County
Rockbridge County gets 4.22 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,232 kWh a year; one kW of the turbine above makes 398. Kilowatt for kilowatt, panels make 3.1 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.