Wind Turbine Payback in Marion County, SC
Wind turbine payback in Marion 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 Marion County, SC averages 4.95 m/s (11.1 mph). A 10 kW turbine there would make about 12,199 kWh a year, worth $1,940 at SC's 15.9¢/kWh. Against an installed cost of about $100,000, that is a payback of 52 years, and the turbine is built to last about 20.
What to do in Marion County
A home turbine is not worth buying for savings in Marion County unless your spot is far windier than the county average, 7.6 m/s at the hub against 4.95 m/s here. Per kW, solar panels would make about 1,329 kWh a year here against the turbine's 1,220, so get a solar quote first.
What would have to change
- Power would have to cost 41¢/kWh, 2.6 times what SC pays now.
- Or the average wind at the hub would have to be 7.6 m/s instead of 4.95. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SC
Marion County is the 1,479th 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 Marion County
April is the strongest month here, at 5.73 m/s and about 1,455 kWh. August is the weakest, 3.94 m/s and 533 kWh, so the best month makes 2.7 times the worst. November to March brings in 49% of the year's output in Marion County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.33 m/s | 1,257 kWh | $200 |
| February | 5.52 m/s | 1,241 kWh | $197 |
| March | 5.62 m/s | 1,433 kWh | $228 |
| April | 5.73 m/s | 1,455 kWh | $231 |
| May | 5.00 m/s | 1,067 kWh | $170 |
| June | 4.34 m/s | 691 kWh | $110 |
| July | 4.20 m/s | 648 kWh | $103 |
| August | 3.94 m/s | 533 kWh | $85 |
| September | 4.71 m/s | 873 kWh | $139 |
| October | 4.88 m/s | 998 kWh | $159 |
| November | 5.07 m/s | 1,072 kWh | $170 |
| December | 5.11 m/s | 1,128 kWh | $179 |
What a taller tower would buy
Measured at 10 m the wind in Marion County averages 3.7 m/s; at 50 m it is 5.67 m/s. That gives a shear exponent of 0.265, typical of ordinary open country. Going from 20 m to 50 m takes output from 9,027 to 17,272 kWh a year, 91% 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 | 4.45 m/s | 9,027 kWh | 70 years |
| 30 m | 4.95 m/s | 12,213 kWh | 52 years |
| 40 m | 5.34 m/s | 14,923 kWh | 42 years |
| 50 m | 5.67 m/s | 17,272 kWh | 36 years |
Counties around Marion County
4 of the 6 closest counties are windier at turbine height; the windiest, Horry County, averages 5.29 m/s.
- Florence County, SC: 4.98 m/s, 12,400 kWh, payback 51 years (21 mi)
- Dillon County, SC: 5 m/s, 12,535 kWh, payback 50 years (21 mi)
- Horry County, SC: 5.29 m/s, 14,538 kWh, payback 43 years (25 mi)
- Williamsburg County, SC: 4.34 m/s, 8,403 kWh, payback 75 years (38 mi)
- Darlington County, SC: 4.46 m/s, 9,100 kWh, payback 69 years (39 mi)
- Marlboro County, SC: 5 m/s, 12,535 kWh, payback 50 years (40 mi)
Sun versus wind in Marion County
Marion County gets 4.55 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,329 kWh a year; one kW of the turbine above makes 1,220. 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.