Wind Turbine Payback in Johnson County, IN
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, IN averages 5.09 m/s (11.4 mph). A 10 kW turbine there would make about 13,146 kWh a year, worth $2,240 at IN's 17.04¢/kWh. Against an installed cost of about $100,000, that is a payback of 45 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, 7.3 m/s at the hub against 5.09 m/s here. Per kW, solar panels would make about 1,168 kWh a year here against the turbine's 1,315, so get a solar quote first.
What would have to change
- Power would have to cost 38¢/kWh, 2.2 times what IN pays now.
- Or the average wind at the hub would have to be 7.3 m/s instead of 5.09. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IN
Johnson County is the 1,408th 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 Johnson County
April is the strongest month here, at 5.96 m/s and about 1,597 kWh. July is the weakest, 3.78 m/s and 471 kWh, so the best month makes 3.4 times the worst. November to March brings in 54% of the year's output in Johnson County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.86 m/s | 1,585 kWh | $270 |
| February | 5.83 m/s | 1,417 kWh | $241 |
| March | 5.82 m/s | 1,563 kWh | $266 |
| April | 5.96 m/s | 1,597 kWh | $272 |
| May | 5.00 m/s | 1,065 kWh | $181 |
| June | 4.33 m/s | 687 kWh | $117 |
| July | 3.78 m/s | 471 kWh | $80 |
| August | 3.81 m/s | 481 kWh | $82 |
| September | 4.33 m/s | 687 kWh | $117 |
| October | 5.20 m/s | 1,181 kWh | $201 |
| November | 5.56 m/s | 1,351 kWh | $230 |
| December | 5.58 m/s | 1,412 kWh | $241 |
What a taller tower would buy
Measured at 10 m the wind in Johnson County averages 3.75 m/s; at 50 m it is 5.86 m/s. That gives a shear exponent of 0.277, typical of ordinary open country. Going from 20 m to 50 m takes output from 9,619 to 18,669 kWh a year, 94% 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 | 4.55 m/s | 9,619 kWh | 61 years |
| 30 m | 5.09 m/s | 13,125 kWh | 45 years |
| 40 m | 5.51 m/s | 16,100 kWh | 37 years |
| 50 m | 5.86 m/s | 18,669 kWh | 31 years |
Counties around Johnson County
3 of the 6 closest counties are windier at turbine height; the windiest, Hancock County, averages 5.87 m/s.
- Shelby County, IN: 5.58 m/s, 16,616 kWh, payback 35 years (16 mi)
- Morgan County, IN: 5.09 m/s, 13,146 kWh, payback 45 years (19 mi)
- Marion County, IN: 5.8 m/s, 18,226 kWh, payback 32 years (20 mi)
- Brown County, IN: 4.32 m/s, 8,289 kWh, payback 71 years (22 mi)
- Bartholomew County, IN: 4.82 m/s, 11,341 kWh, payback 52 years (23 mi)
- Hancock County, IN: 5.87 m/s, 18,742 kWh, payback 31 years (28 mi)
Sun versus wind in Johnson County
Johnson County gets 4 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,168 kWh a year; one kW of the turbine above makes 1,315. 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.