Wind Turbine Payback in McMullen County, TX
Wind turbine payback in McMullen 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 McMullen County, TX averages 5.49 m/s (12.3 mph). A 10 kW turbine there would make about 15,965 kWh a year, worth $2,559 at TX's 16.03¢/kWh. Against an installed cost of about $100,000, that is a payback of 39 years, and the turbine is built to last about 20.
What to do in McMullen County
A home turbine is not worth buying for savings in McMullen County unless your spot is far windier than the county average, 7.6 m/s at the hub against 5.49 m/s here. Per kW, solar panels would make about 1,434 kWh a year here against the turbine's 1,597, so get a solar quote first.
What would have to change
- Power would have to cost 31¢/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 5.49. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TX
McMullen County is the 1,228th 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 McMullen County
May is the strongest month here, at 6.13 m/s and about 1,754 kWh. September is the weakest, 4.81 m/s and 929 kWh, so the best month makes 1.9 times the worst. November to March brings in 41% of the year's output in McMullen County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.28 m/s | 1,228 kWh | $197 |
| February | 5.55 m/s | 1,256 kWh | $201 |
| March | 5.91 m/s | 1,619 kWh | $260 |
| April | 6.20 m/s | 1,741 kWh | $279 |
| May | 6.13 m/s | 1,754 kWh | $281 |
| June | 5.71 m/s | 1,442 kWh | $231 |
| July | 5.48 m/s | 1,353 kWh | $217 |
| August | 5.10 m/s | 1,123 kWh | $180 |
| September | 4.81 m/s | 929 kWh | $149 |
| October | 5.24 m/s | 1,207 kWh | $193 |
| November | 5.31 m/s | 1,209 kWh | $194 |
| December | 5.22 m/s | 1,191 kWh | $191 |
What a taller tower would buy
Measured at 10 m the wind in McMullen County averages 4.31 m/s; at 50 m it is 6.15 m/s. That gives a shear exponent of 0.221, typical of ordinary open country. Going from 20 m to 50 m takes output from 12,687 to 20,816 kWh a year, 64% 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 | 5.02 m/s | 12,687 kWh | 49 years |
| 30 m | 5.49 m/s | 15,990 kWh | 39 years |
| 40 m | 5.85 m/s | 18,625 kWh | 34 years |
| 50 m | 6.15 m/s | 20,816 kWh | 30 years |
Counties around McMullen County
3 of the 6 closest counties are windier at turbine height; the windiest, Duval County, averages 5.98 m/s.
- Live Oak County, TX: 5.6 m/s, 16,762 kWh, payback 37 years (28 mi)
- La Salle County, TX: 5.41 m/s, 15,390 kWh, payback 41 years (32 mi)
- Atascosa County, TX: 5.31 m/s, 14,679 kWh, payback 43 years (35 mi)
- Frio County, TX: 5.29 m/s, 14,538 kWh, payback 43 years (46 mi)
- Duval County, TX: 5.98 m/s, 19,556 kWh, payback 32 years (49 mi)
- Bee County, TX: 5.6 m/s, 16,762 kWh, payback 37 years (51 mi)
Sun versus wind in McMullen County
McMullen County gets 4.91 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,434 kWh a year; one kW of the turbine above makes 1,597. 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.