Wind Turbine Payback in Williamsburg County, SC
Wind turbine payback in Williamsburg 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 Williamsburg County, SC averages 4.34 m/s (9.7 mph). A 10 kW turbine there would make about 8,403 kWh a year, worth $1,336 at SC's 15.9¢/kWh. Against an installed cost of about $100,000, that is a payback of 75 years, and the turbine is built to last about 20.
What to do in Williamsburg County
A home turbine is not worth buying for savings in Williamsburg County unless your spot is far windier than the county average, 7.6 m/s at the hub against 4.34 m/s here. Per kW, solar panels would make about 1,349 kWh a year here against the turbine's 840, so get a solar quote first.
What would have to change
- Power would have to cost 60¢/kWh, 3.7 times what SC pays now.
- Or the average wind at the hub would have to be 7.6 m/s instead of 4.34. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SC
Williamsburg County is the 1,867th 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 Williamsburg County
March is the strongest month here, at 4.93 m/s and about 1,028 kWh. August is the weakest, 3.49 m/s and 363 kWh, so the best month makes 2.8 times the worst. November to March brings in 50% of the year's output in Williamsburg County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.66 m/s | 876 kWh | $139 |
| February | 4.81 m/s | 867 kWh | $138 |
| March | 4.93 m/s | 1,028 kWh | $163 |
| April | 4.99 m/s | 1,023 kWh | $163 |
| May | 4.41 m/s | 747 kWh | $119 |
| June | 3.84 m/s | 476 kWh | $76 |
| July | 3.72 m/s | 446 kWh | $71 |
| August | 3.49 m/s | 363 kWh | $58 |
| September | 4.13 m/s | 597 kWh | $95 |
| October | 4.28 m/s | 685 kWh | $109 |
| November | 4.44 m/s | 740 kWh | $118 |
| December | 4.46 m/s | 773 kWh | $123 |
What a taller tower would buy
Measured at 10 m the wind in Williamsburg County averages 3.16 m/s; at 50 m it is 5.03 m/s. That gives a shear exponent of 0.289, typical of ordinary open country. Going from 20 m to 50 m takes output from 5,893 to 12,737 kWh a year, 116% 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 | 3.86 m/s | 5,893 kWh | over 100 years |
| 30 m | 4.34 m/s | 8,401 kWh | 75 years |
| 40 m | 4.72 m/s | 10,672 kWh | 59 years |
| 50 m | 5.03 m/s | 12,737 kWh | 49 years |
Counties around Williamsburg County
4 of the 6 closest counties are windier at turbine height; the windiest, Florence County, averages 4.98 m/s.
- Florence County, SC: 4.98 m/s, 12,400 kWh, payback 51 years (28 mi)
- Georgetown County, SC: 4.38 m/s, 8,632 kWh, payback 73 years (28 mi)
- Clarendon County, SC: 4.34 m/s, 8,403 kWh, payback 75 years (29 mi)
- Berkeley County, SC: 4.13 m/s, 7,248 kWh, payback 87 years (32 mi)
- Marion County, SC: 4.95 m/s, 12,199 kWh, payback 52 years (38 mi)
- Sumter County, SC: 4.7 m/s, 10,571 kWh, payback 60 years (43 mi)
Sun versus wind in Williamsburg County
Williamsburg County gets 4.62 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,349 kWh a year; one kW of the turbine above makes 840. Kilowatt for kilowatt, panels make 1.6 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.