Wind Turbine Payback in Fairfax city, VA
Wind turbine payback in Fairfax city
No. The turbine wears out before it pays for itself.
At 30 m, the height a home turbine tower usually reaches, the wind in Fairfax city, VA averages 4.57 m/s (10.2 mph). A 10 kW turbine there would make about 9,763 kWh a year, worth $1,655 at VA's 16.95¢/kWh. Against an installed cost of about $100,000, that is a payback of 60 years, and the turbine is built to last about 20.
What to do in Fairfax city
A home turbine is not worth buying for savings in Fairfax city unless your spot is far windier than the county average, 7.3 m/s at the hub against 4.57 m/s here. Per kW, solar panels would make about 1,203 kWh a year here against the turbine's 976, so get a solar quote first.
What would have to change
- Power would have to cost 51¢/kWh, 3.0 times what VA pays now.
- Or the average wind at the hub would have to be 7.3 m/s instead of 4.57. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of VA
Fairfax city is the 1,704th 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 Fairfax city
March is the strongest month here, at 5.42 m/s and about 1,314 kWh. August is the weakest, 3.43 m/s and 346 kWh, so the best month makes 3.8 times the worst. November to March brings in 57% of the year's output in Fairfax city.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.34 m/s | 1,267 kWh | $215 |
| February | 5.45 m/s | 1,201 kWh | $204 |
| March | 5.42 m/s | 1,314 kWh | $223 |
| April | 5.18 m/s | 1,132 kWh | $192 |
| May | 4.33 m/s | 708 kWh | $120 |
| June | 3.87 m/s | 489 kWh | $83 |
| July | 3.45 m/s | 351 kWh | $59 |
| August | 3.43 m/s | 346 kWh | $59 |
| September | 3.97 m/s | 527 kWh | $89 |
| October | 4.56 m/s | 824 kWh | $140 |
| November | 4.90 m/s | 973 kWh | $165 |
| December | 4.98 m/s | 1,055 kWh | $179 |
What a taller tower would buy
Measured at 10 m the wind in Fairfax city averages 3.31 m/s; at 50 m it is 5.31 m/s. That gives a shear exponent of 0.294, typical of ordinary open country. Going from 20 m to 50 m takes output from 6,862 to 14,679 kWh a year, 114% 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 | 4.06 m/s | 6,862 kWh | 86 years |
| 30 m | 4.57 m/s | 9,760 kWh | 60 years |
| 40 m | 4.97 m/s | 12,352 kWh | 48 years |
| 50 m | 5.31 m/s | 14,679 kWh | 40 years |
Counties around Fairfax city
3 of the 6 closest counties are windier at turbine height; the windiest, Falls Church city, averages 5.23 m/s.
- Fairfax County, VA: 4.57 m/s, 9,763 kWh, payback 60 years (2 mi)
- Falls Church city, VA: 5.23 m/s, 14,116 kWh, payback 42 years (7 mi)
- Manassas Park city, VA: 4.57 m/s, 9,763 kWh, payback 60 years (10 mi)
- Arlington County, VA: 5.23 m/s, 14,116 kWh, payback 42 years (11 mi)
- Alexandria city, VA: 5.23 m/s, 14,116 kWh, payback 42 years (12 mi)
- Manassas city, VA: 3.65 m/s, 4,948 kWh, payback over 100 years (12 mi)
Sun versus wind in Fairfax city
Fairfax city gets 4.12 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,203 kWh a year; one kW of the turbine above makes 976. Kilowatt for kilowatt, panels make 1.2 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.