Wind Turbine Payback in Karnes County, TX
Wind turbine payback in Karnes 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 Karnes County, TX averages 5.39 m/s (12.1 mph). A 10 kW turbine there would make about 15,247 kWh a year, worth $2,444 at TX's 16.03¢/kWh. Against an installed cost of about $100,000, that is a payback of 41 years, and the turbine is built to last about 20.
What to do in Karnes County
A home turbine is not worth buying for savings in Karnes County unless your spot is far windier than the county average, 7.6 m/s at the hub against 5.39 m/s here. Per kW, solar panels would make about 1,405 kWh a year here against the turbine's 1,525, so get a solar quote first.
What would have to change
- Power would have to cost 33¢/kWh, 2.0 times what TX pays now.
- Or the average wind at the hub would have to be 7.6 m/s instead of 5.39. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TX
Karnes County is the 1,288th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in TX is Dallam County at 6.82 m/s, payback 24 years.
Month by month in Karnes County
April is the strongest month here, at 6.11 m/s and about 1,684 kWh. September is the weakest, 4.62 m/s and 828 kWh, so the best month makes 2.0 times the worst. November to March brings in 45% of the year's output in Karnes County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.50 m/s | 1,363 kWh | $218 |
| February | 5.71 m/s | 1,350 kWh | $216 |
| March | 5.93 m/s | 1,628 kWh | $261 |
| April | 6.11 m/s | 1,684 kWh | $270 |
| May | 5.90 m/s | 1,611 kWh | $258 |
| June | 5.24 m/s | 1,168 kWh | $187 |
| July | 4.94 m/s | 1,031 kWh | $165 |
| August | 4.65 m/s | 870 kWh | $139 |
| September | 4.62 m/s | 828 kWh | $133 |
| October | 5.16 m/s | 1,159 kWh | $186 |
| November | 5.44 m/s | 1,282 kWh | $206 |
| December | 5.46 m/s | 1,335 kWh | $214 |
What a taller tower would buy
Measured at 10 m the wind in Karnes County averages 4.18 m/s; at 50 m it is 6.06 m/s. That gives a shear exponent of 0.231, typical of ordinary open country. Going from 20 m to 50 m takes output from 11,893 to 20,149 kWh a year, 69% 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 | 4.9 m/s | 11,893 kWh | 53 years |
| 30 m | 5.39 m/s | 15,215 kWh | 41 years |
| 40 m | 5.76 m/s | 17,899 kWh | 35 years |
| 50 m | 6.06 m/s | 20,149 kWh | 31 years |
Counties around Karnes County
4 of the 6 closest counties are windier at turbine height; the windiest, Goliad County, averages 5.6 m/s.
- Wilson County, TX: 5.39 m/s, 15,247 kWh, payback 41 years (23 mi)
- Goliad County, TX: 5.6 m/s, 16,762 kWh, payback 37 years (31 mi)
- DeWitt County, TX: 5.46 m/s, 15,749 kWh, payback 40 years (32 mi)
- Bee County, TX: 5.6 m/s, 16,762 kWh, payback 37 years (35 mi)
- Atascosa County, TX: 5.31 m/s, 14,679 kWh, payback 43 years (41 mi)
- Live Oak County, TX: 5.6 m/s, 16,762 kWh, payback 37 years (42 mi)
Sun versus wind in Karnes County
Karnes County gets 4.81 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,405 kWh a year; one kW of the turbine above makes 1,525. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.1 times. 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.