Wind Turbine Payback in Sullivan County, IN
Wind turbine payback in Sullivan 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 Sullivan County, IN averages 5.61 m/s (12.5 mph). A 10 kW turbine there would make about 16,834 kWh a year, worth $2,869 at IN's 17.04¢/kWh. Against an installed cost of about $100,000, that is a payback of 35 years, and the turbine is built to last about 20.
What to do in Sullivan County
A home turbine is not worth buying for savings in Sullivan County unless your spot is far windier than the county average, 7.3 m/s at the hub against 5.61 m/s here. Per kW, solar panels would make about 1,180 kWh a year here against the turbine's 1,683, so get a solar quote first.
What would have to change
- Power would have to cost 30¢/kWh, 1.7 times what IN pays now.
- Or the average wind at the hub would have to be 7.3 m/s instead of 5.61. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IN
Sullivan County is the 1,161st windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in IN is Lake County at 6.17 m/s, payback 28 years.
Month by month in Sullivan County
April is the strongest month here, at 6.64 m/s and about 2,011 kWh. August is the weakest, 4.15 m/s and 623 kWh, so the best month makes 3.2 times the worst. November to March brings in 53% of the year's output in Sullivan County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.35 m/s | 1,896 kWh | $323 |
| February | 6.33 m/s | 1,697 kWh | $289 |
| March | 6.43 m/s | 1,946 kWh | $332 |
| April | 6.64 m/s | 2,011 kWh | $343 |
| May | 5.65 m/s | 1,453 kWh | $248 |
| June | 4.85 m/s | 950 kWh | $162 |
| July | 4.15 m/s | 623 kWh | $106 |
| August | 4.15 m/s | 623 kWh | $106 |
| September | 4.72 m/s | 880 kWh | $150 |
| October | 5.79 m/s | 1,541 kWh | $263 |
| November | 6.22 m/s | 1,754 kWh | $299 |
| December | 6.12 m/s | 1,751 kWh | $298 |
What a taller tower would buy
Measured at 10 m the wind in Sullivan County averages 4.29 m/s; at 50 m it is 6.36 m/s. That gives a shear exponent of 0.245, typical of ordinary open country. Going from 20 m to 50 m takes output from 13,086 to 22,373 kWh a year, 71% 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 | 5.08 m/s | 13,086 kWh | 45 years |
| 30 m | 5.61 m/s | 16,848 kWh | 35 years |
| 40 m | 6.02 m/s | 19,864 kWh | 30 years |
| 50 m | 6.36 m/s | 22,373 kWh | 26 years |
Counties around Sullivan County
2 of the 6 closest counties are windier at turbine height; the windiest, Vigo County, averages 5.76 m/s.
- Crawford County, IL: 5.61 m/s, 16,834 kWh, payback 31 years (19 mi)
- Greene County, IN: 4.68 m/s, 10,445 kWh, payback 56 years (22 mi)
- Vigo County, IN: 5.76 m/s, 17,932 kWh, payback 33 years (24 mi)
- Clark County, IL: 5.76 m/s, 17,932 kWh, payback 29 years (26 mi)
- Clay County, IN: 5.14 m/s, 13,490 kWh, payback 44 years (26 mi)
- Knox County, IN: 5.53 m/s, 16,254 kWh, payback 36 years (28 mi)
Sun versus wind in Sullivan County
Sullivan County gets 4.04 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,180 kWh a year; one kW of the turbine above makes 1,683. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.4 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.