Wind Turbine Payback in Johnson County, GA
Wind turbine payback in Johnson 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 Johnson County, GA averages 4.79 m/s (10.7 mph). A 10 kW turbine there would make about 11,147 kWh a year, worth $1,726 at GA's 15.48¢/kWh. Against an installed cost of about $100,000, that is a payback of 58 years, and the turbine is built to last about 20.
What to do in Johnson County
A home turbine is not worth buying for savings in Johnson County unless your spot is far windier than the county average, 7.8 m/s at the hub against 4.79 m/s here. Per kW, solar panels would make about 1,369 kWh a year here against the turbine's 1,115, so get a solar quote first.
What would have to change
- Power would have to cost 45¢/kWh, 2.9 times what GA pays now.
- Or the average wind at the hub would have to be 7.8 m/s instead of 4.79. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of GA
Johnson County is the 1,566th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in GA is Glynn County at 5.08 m/s, payback 49 years.
Month by month in Johnson County
March is the strongest month here, at 5.53 m/s and about 1,378 kWh. August is the weakest, 3.76 m/s and 462 kWh, so the best month makes 3.0 times the worst. November to March brings in 52% of the year's output in Johnson County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.32 m/s | 1,256 kWh | $194 |
| February | 5.35 m/s | 1,148 kWh | $178 |
| March | 5.53 m/s | 1,378 kWh | $213 |
| April | 5.37 m/s | 1,241 kWh | $192 |
| May | 4.78 m/s | 939 kWh | $145 |
| June | 4.11 m/s | 588 kWh | $91 |
| July | 3.88 m/s | 511 kWh | $79 |
| August | 3.76 m/s | 462 kWh | $72 |
| September | 4.53 m/s | 783 kWh | $121 |
| October | 4.78 m/s | 943 kWh | $146 |
| November | 5.05 m/s | 1,061 kWh | $164 |
| December | 5.09 m/s | 1,116 kWh | $173 |
What a taller tower would buy
Measured at 10 m the wind in Johnson County averages 3.58 m/s; at 50 m it is 5.49 m/s. That gives a shear exponent of 0.266, typical of ordinary open country. Going from 20 m to 50 m takes output from 8,190 to 15,965 kWh a year, 95% 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 | 4.3 m/s | 8,190 kWh | 79 years |
| 30 m | 4.79 m/s | 11,163 kWh | 58 years |
| 40 m | 5.17 m/s | 13,723 kWh | 47 years |
| 50 m | 5.49 m/s | 15,965 kWh | 41 years |
Counties around Johnson County
None of the 6 closest counties is windier than Johnson County.
- Treutlen County, GA: 4.79 m/s, 11,147 kWh, payback 58 years (20 mi)
- Washington County, GA: 4.34 m/s, 8,403 kWh, payback 77 years (21 mi)
- Emanuel County, GA: 4.79 m/s, 11,147 kWh, payback 58 years (22 mi)
- Laurens County, GA: 3.94 m/s, 6,280 kWh, payback over 100 years (26 mi)
- Jefferson County, GA: 4.34 m/s, 8,403 kWh, payback 77 years (29 mi)
- Wilkinson County, GA: 3.33 m/s, 3,684 kWh, payback over 100 years (31 mi)
Sun versus wind in Johnson County
Johnson County gets 4.69 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,369 kWh a year; one kW of the turbine above makes 1,115. Kilowatt for kilowatt, panels make 1.2 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.