Wind Turbine Payback in Guilford County, NC
Wind turbine payback in Guilford 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 Guilford County, NC averages 4.47 m/s (10 mph). A 10 kW turbine there would make about 9,160 kWh a year, worth $1,368 at NC's 14.94¢/kWh. Against an installed cost of about $100,000, that is a payback of 73 years, and the turbine is built to last about 20.
What to do in Guilford County
A home turbine is not worth buying for savings in Guilford County unless your spot is far windier than the county average, 7.9 m/s at the hub against 4.47 m/s here. Per kW, solar panels would make about 1,267 kWh a year here against the turbine's 916, so get a solar quote first.
What would have to change
- Power would have to cost 55¢/kWh, 3.7 times what NC pays now.
- Or the average wind at the hub would have to be 7.9 m/s instead of 4.47. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of NC
Guilford County is the 1,760th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in NC is Dare County at 6.91 m/s, payback 25 years.
Month by month in Guilford County
March is the strongest month here, at 5.29 m/s and about 1,237 kWh. August is the weakest, 3.30 m/s and 303 kWh, so the best month makes 4.1 times the worst. November to March brings in 54% of the year's output in Guilford County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.02 m/s | 1,075 kWh | $161 |
| February | 5.22 m/s | 1,076 kWh | $161 |
| March | 5.29 m/s | 1,237 kWh | $185 |
| April | 5.34 m/s | 1,222 kWh | $183 |
| May | 4.44 m/s | 762 kWh | $114 |
| June | 3.78 m/s | 455 kWh | $68 |
| July | 3.44 m/s | 347 kWh | $52 |
| August | 3.30 m/s | 303 kWh | $45 |
| September | 3.98 m/s | 533 kWh | $80 |
| October | 4.43 m/s | 758 kWh | $113 |
| November | 4.65 m/s | 846 kWh | $126 |
| December | 4.73 m/s | 915 kWh | $137 |
What a taller tower would buy
Measured at 10 m the wind in Guilford County averages 3.26 m/s; at 50 m it is 5.17 m/s. That gives a shear exponent of 0.287, typical of ordinary open country. Going from 20 m to 50 m takes output from 6,450 to 13,698 kWh a year, 112% 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 | 3.97 m/s | 6,450 kWh | over 100 years |
| 30 m | 4.46 m/s | 9,130 kWh | 73 years |
| 40 m | 4.85 m/s | 11,533 kWh | 58 years |
| 50 m | 5.17 m/s | 13,698 kWh | 49 years |
Counties around Guilford County
None of the 6 closest counties is windier than Guilford County.
- Rockingham County, NC: 3.73 m/s, 5,297 kWh, payback over 100 years (21 mi)
- Alamance County, NC: 3.82 m/s, 5,707 kWh, payback over 100 years (22 mi)
- Randolph County, NC: 3.74 m/s, 5,342 kWh, payback over 100 years (26 mi)
- Forsyth County, NC: 4.47 m/s, 9,160 kWh, payback 73 years (26 mi)
- Davidson County, NC: 4.47 m/s, 9,160 kWh, payback 73 years (31 mi)
- Caswell County, NC: 3.86 m/s, 5,894 kWh, payback over 100 years (33 mi)
Sun versus wind in Guilford County
Guilford County gets 4.34 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,267 kWh a year; one kW of the turbine above makes 916. Kilowatt for kilowatt, panels make 1.4 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.