Wind Turbine Payback in Prince William County, VA
Wind turbine payback in Prince William 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 Prince William County, VA averages 3.65 m/s (8.2 mph). A 10 kW turbine there would make about 4,948 kWh a year, worth $839 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 Prince William County
A home turbine is not worth buying for savings in Prince William County unless your spot is far windier than the county average, 7.3 m/s at the hub against 3.65 m/s here. Per kW, solar panels would make about 1,203 kWh a year here against the turbine's 495, so get a solar quote first.
What would have to change
- Power would have to cost 101¢/kWh, 6.0 times what VA pays now.
- Or the average wind at the hub would have to be 7.3 m/s instead of 3.65. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of VA
Prince William County is the 2,332nd 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 Prince William County
March is the strongest month here, at 4.32 m/s and about 704 kWh. August is the weakest, 2.80 m/s and 175 kWh, so the best month makes 4.0 times the worst. November to March brings in 57% of the year's output in Prince William County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.16 m/s | 631 kWh | $107 |
| February | 4.31 m/s | 632 kWh | $107 |
| March | 4.32 m/s | 704 kWh | $119 |
| April | 4.14 m/s | 600 kWh | $102 |
| May | 3.47 m/s | 357 kWh | $61 |
| June | 3.14 m/s | 249 kWh | $42 |
| July | 2.82 m/s | 178 kWh | $30 |
| August | 2.80 m/s | 175 kWh | $30 |
| September | 3.24 m/s | 276 kWh | $47 |
| October | 3.64 m/s | 417 kWh | $71 |
| November | 3.86 m/s | 485 kWh | $82 |
| December | 3.86 m/s | 501 kWh | $85 |
What a taller tower would buy
Measured at 10 m the wind in Prince William County averages 2.38 m/s; at 50 m it is 4.45 m/s. That gives a shear exponent of 0.389, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 2,956 to 9,041 kWh a year, 206% 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 | 3.12 m/s | 2,956 kWh | over 100 years |
| 30 m | 3.65 m/s | 4,939 kWh | over 100 years |
| 40 m | 4.08 m/s | 6,986 kWh | 84 years |
| 50 m | 4.45 m/s | 9,041 kWh | 65 years |
Counties around Prince William County
3 of the 6 closest counties are windier at turbine height; the windiest, Manassas Park city, averages 4.57 m/s.
- Manassas city, VA: 3.65 m/s, 4,948 kWh, payback over 100 years (3 mi)
- Manassas Park city, VA: 4.57 m/s, 9,763 kWh, payback 60 years (5 mi)
- Fairfax County, VA: 4.57 m/s, 9,763 kWh, payback 60 years (14 mi)
- Fairfax city, VA: 4.57 m/s, 9,763 kWh, payback 60 years (14 mi)
- Fauquier County, VA: 3.31 m/s, 3,612 kWh, payback over 100 years (19 mi)
- Stafford County, VA: 3.65 m/s, 4,948 kWh, payback over 100 years (19 mi)
Sun versus wind in Prince William County
Prince William County 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 495. Kilowatt for kilowatt, panels make 2.4 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.