Wind Turbine Payback in Barnwell County, SC
Wind turbine payback in Barnwell 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 Barnwell County, SC averages 4.59 m/s (10.3 mph). A 10 kW turbine there would make about 9,885 kWh a year, worth $1,572 at SC's 15.9¢/kWh. Against an installed cost of about $100,000, that is a payback of 64 years, and the turbine is built to last about 20.
What to do in Barnwell County
A home turbine is not worth buying for savings in Barnwell County unless your spot is far windier than the county average, 7.6 m/s at the hub against 4.59 m/s here. Per kW, solar panels would make about 1,352 kWh a year here against the turbine's 989, so get a solar quote first.
What would have to change
- Power would have to cost 51¢/kWh, 3.2 times what SC pays now.
- Or the average wind at the hub would have to be 7.6 m/s instead of 4.59. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SC
Barnwell County is the 1,698th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in SC is Beaufort County at 5.71 m/s, payback 36 years.
Month by month in Barnwell County
March is the strongest month here, at 5.32 m/s and about 1,254 kWh. August is the weakest, 3.60 m/s and 401 kWh, so the best month makes 3.1 times the worst. November to March brings in 52% of the year's output in Barnwell County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.08 m/s | 1,110 kWh | $176 |
| February | 5.21 m/s | 1,072 kWh | $170 |
| March | 5.32 m/s | 1,254 kWh | $199 |
| April | 5.28 m/s | 1,189 kWh | $189 |
| May | 4.56 m/s | 822 kWh | $131 |
| June | 3.95 m/s | 519 kWh | $83 |
| July | 3.76 m/s | 463 kWh | $74 |
| August | 3.60 m/s | 401 kWh | $64 |
| September | 4.30 m/s | 674 kWh | $107 |
| October | 4.56 m/s | 822 kWh | $131 |
| November | 4.76 m/s | 898 kWh | $143 |
| December | 4.83 m/s | 967 kWh | $154 |
What a taller tower would buy
Measured at 10 m the wind in Barnwell County averages 3.41 m/s; at 50 m it is 5.27 m/s. That gives a shear exponent of 0.270, typical of ordinary open country. Going from 20 m to 50 m takes output from 7,169 to 14,397 kWh a year, 101% 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 | 4.11 m/s | 7,169 kWh | 88 years |
| 30 m | 4.59 m/s | 9,892 kWh | 64 years |
| 40 m | 4.96 m/s | 12,278 kWh | 51 years |
| 50 m | 5.27 m/s | 14,397 kWh | 44 years |
Counties around Barnwell County
2 of the 6 closest counties are windier at turbine height; the windiest, Burke County, averages 4.77 m/s.
- Allendale County, SC: 4.02 m/s, 6,678 kWh, payback 94 years (20 mi)
- Bamberg County, SC: 4.02 m/s, 6,678 kWh, payback 94 years (22 mi)
- Aiken County, SC: 4.27 m/s, 8,008 kWh, payback 79 years (23 mi)
- Burke County, GA: 4.77 m/s, 11,018 kWh, payback 59 years (36 mi)
- Screven County, GA: 4.67 m/s, 10,382 kWh, payback 62 years (37 mi)
- Hampton County, SC: 4.02 m/s, 6,678 kWh, payback 94 years (37 mi)
Sun versus wind in Barnwell County
Barnwell County gets 4.63 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,352 kWh a year; one kW of the turbine above makes 989. 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.