Wind Turbine Payback in Harnett County, NC
Wind turbine payback in Harnett 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 Harnett County, NC averages 4.39 m/s (9.8 mph). A 10 kW turbine there would make about 8,690 kWh a year, worth $1,298 at NC's 14.94¢/kWh. Against an installed cost of about $100,000, that is a payback of 77 years, and the turbine is built to last about 20.
What to do in Harnett County
A home turbine is not worth buying for savings in Harnett County unless your spot is far windier than the county average, 7.9 m/s at the hub against 4.39 m/s here. Per kW, solar panels would make about 1,305 kWh a year here against the turbine's 869, so get a solar quote first.
What would have to change
- Power would have to cost 58¢/kWh, 3.9 times what NC pays now.
- Or the average wind at the hub would have to be 7.9 m/s instead of 4.39. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of NC
Harnett County is the 1,825th 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 Harnett County
March is the strongest month here, at 5.06 m/s and about 1,100 kWh. August is the weakest, 3.45 m/s and 349 kWh, so the best month makes 3.2 times the worst. November to March brings in 51% of the year's output in Harnett County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.78 m/s | 940 kWh | $140 |
| February | 4.98 m/s | 949 kWh | $142 |
| March | 5.06 m/s | 1,100 kWh | $164 |
| April | 5.12 m/s | 1,098 kWh | $164 |
| May | 4.41 m/s | 748 kWh | $112 |
| June | 3.83 m/s | 473 kWh | $71 |
| July | 3.61 m/s | 405 kWh | $61 |
| August | 3.45 m/s | 349 kWh | $52 |
| September | 4.05 m/s | 562 kWh | $84 |
| October | 4.30 m/s | 694 kWh | $104 |
| November | 4.51 m/s | 774 kWh | $116 |
| December | 4.57 m/s | 831 kWh | $124 |
What a taller tower would buy
Measured at 10 m the wind in Harnett County averages 3.13 m/s; at 50 m it is 5.13 m/s. That gives a shear exponent of 0.307, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 5,952 to 13,421 kWh a year, 125% 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 | 3.87 m/s | 5,952 kWh | over 100 years |
| 30 m | 4.39 m/s | 8,664 kWh | 77 years |
| 40 m | 4.79 m/s | 11,149 kWh | 60 years |
| 50 m | 5.13 m/s | 13,421 kWh | 50 years |
Counties around Harnett County
3 of the 6 closest counties are windier at turbine height; the windiest, Johnston County, averages 5.2 m/s.
- Lee County, NC: 3.54 m/s, 4,489 kWh, payback over 100 years (18 mi)
- Cumberland County, NC: 4.96 m/s, 12,266 kWh, payback 55 years (22 mi)
- Johnston County, NC: 5.2 m/s, 13,907 kWh, payback 48 years (30 mi)
- Chatham County, NC: 3.54 m/s, 4,489 kWh, payback over 100 years (32 mi)
- Wake County, NC: 3.47 m/s, 4,211 kWh, payback over 100 years (32 mi)
- Hoke County, NC: 4.43 m/s, 8,924 kWh, payback 75 years (32 mi)
Sun versus wind in Harnett County
Harnett County gets 4.47 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,305 kWh a year; one kW of the turbine above makes 869. Kilowatt for kilowatt, panels make 1.5 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.