Wind Turbine Payback in Sampson County, NC
Wind turbine payback in Sampson 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 Sampson County, NC averages 4.9 m/s (11 mph). A 10 kW turbine there would make about 11,866 kWh a year, worth $1,773 at NC's 14.94¢/kWh. Against an installed cost of about $100,000, that is a payback of 56 years, and the turbine is built to last about 20.
What to do in Sampson County
A home turbine is not worth buying for savings in Sampson County unless your spot is far windier than the county average, 7.9 m/s at the hub against 4.9 m/s here. Per kW, solar panels would make about 1,320 kWh a year here against the turbine's 1,187, so get a solar quote first.
What would have to change
- Power would have to cost 42¢/kWh, 2.8 times what NC pays now.
- Or the average wind at the hub would have to be 7.9 m/s instead of 4.9. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of NC
Sampson County is the 1,502nd 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 Sampson County
March is the strongest month here, at 5.63 m/s and about 1,444 kWh. August is the weakest, 3.84 m/s and 491 kWh, so the best month makes 2.9 times the worst. November to March brings in 50% of the year's output in Sampson County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.29 m/s | 1,237 kWh | $185 |
| February | 5.54 m/s | 1,251 kWh | $187 |
| March | 5.63 m/s | 1,444 kWh | $216 |
| April | 5.69 m/s | 1,434 kWh | $214 |
| May | 4.91 m/s | 1,013 kWh | $151 |
| June | 4.27 m/s | 660 kWh | $99 |
| July | 4.12 m/s | 609 kWh | $91 |
| August | 3.84 m/s | 491 kWh | $73 |
| September | 4.60 m/s | 820 kWh | $123 |
| October | 4.82 m/s | 965 kWh | $144 |
| November | 5.04 m/s | 1,053 kWh | $157 |
| December | 5.08 m/s | 1,113 kWh | $166 |
What a taller tower would buy
Measured at 10 m the wind in Sampson County averages 3.65 m/s; at 50 m it is 5.62 m/s. That gives a shear exponent of 0.268, typical of ordinary open country. Going from 20 m to 50 m takes output from 8,727 to 16,907 kWh a year, 94% 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 | 4.4 m/s | 8,727 kWh | 77 years |
| 30 m | 4.9 m/s | 11,873 kWh | 56 years |
| 40 m | 5.29 m/s | 14,564 kWh | 46 years |
| 50 m | 5.62 m/s | 16,907 kWh | 40 years |
Counties around Sampson County
3 of the 6 closest counties are windier at turbine height; the windiest, Wayne County, averages 5.2 m/s.
- Duplin County, NC: 4.9 m/s, 11,866 kWh, payback 56 years (25 mi)
- Cumberland County, NC: 4.96 m/s, 12,266 kWh, payback 55 years (26 mi)
- Bladen County, NC: 4.42 m/s, 8,865 kWh, payback 76 years (29 mi)
- Wayne County, NC: 5.2 m/s, 13,907 kWh, payback 48 years (32 mi)
- Johnston County, NC: 5.2 m/s, 13,907 kWh, payback 48 years (36 mi)
- Harnett County, NC: 4.39 m/s, 8,690 kWh, payback 77 years (39 mi)
Sun versus wind in Sampson County
Sampson County gets 4.52 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,320 kWh a year; one kW of the turbine above makes 1,187. Kilowatt for kilowatt, panels make 1.1 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.