Wind Turbine Payback in Shelby County, IN
Wind turbine payback in Shelby 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 Shelby County, IN averages 5.58 m/s (12.5 mph). A 10 kW turbine there would make about 16,616 kWh a year, worth $2,831 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 Shelby County
A home turbine is not worth buying for savings in Shelby County unless your spot is far windier than the county average, 7.3 m/s at the hub against 5.58 m/s here. Per kW, solar panels would make about 1,165 kWh a year here against the turbine's 1,662, so get a solar quote first.
What would have to change
- Power would have to cost 30¢/kWh, 1.8 times what IN pays now.
- Or the average wind at the hub would have to be 7.3 m/s instead of 5.58. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IN
Shelby County is the 1,176th 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 Shelby County
January is the strongest month here, at 6.44 m/s and about 1,953 kWh. July is the weakest, 4.14 m/s and 620 kWh, so the best month makes 3.1 times the worst. November to March brings in 54% of the year's output in Shelby County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.44 m/s | 1,953 kWh | $333 |
| February | 6.37 m/s | 1,719 kWh | $293 |
| March | 6.36 m/s | 1,898 kWh | $323 |
| April | 6.54 m/s | 1,949 kWh | $332 |
| May | 5.48 m/s | 1,351 kWh | $230 |
| June | 4.78 m/s | 909 kWh | $155 |
| July | 4.14 m/s | 620 kWh | $106 |
| August | 4.15 m/s | 624 kWh | $106 |
| September | 4.74 m/s | 890 kWh | $152 |
| October | 5.73 m/s | 1,504 kWh | $256 |
| November | 6.14 m/s | 1,708 kWh | $291 |
| December | 6.16 m/s | 1,776 kWh | $303 |
What a taller tower would buy
Measured at 10 m the wind in Shelby County averages 4.27 m/s; at 50 m it is 6.32 m/s. That gives a shear exponent of 0.244, typical of ordinary open country. Going from 20 m to 50 m takes output from 12,899 to 22,077 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 | 5.05 m/s | 12,899 kWh | 46 years |
| 30 m | 5.58 m/s | 16,612 kWh | 35 years |
| 40 m | 5.99 m/s | 19,594 kWh | 30 years |
| 50 m | 6.32 m/s | 22,077 kWh | 27 years |
Counties around Shelby County
2 of the 6 closest counties are windier at turbine height; the windiest, Hancock County, averages 5.87 m/s.
- Johnson County, IN: 5.09 m/s, 13,146 kWh, payback 45 years (16 mi)
- Rush County, IN: 5.58 m/s, 16,616 kWh, payback 35 years (19 mi)
- Hancock County, IN: 5.87 m/s, 18,742 kWh, payback 31 years (21 mi)
- Decatur County, IN: 5.58 m/s, 16,616 kWh, payback 35 years (22 mi)
- Bartholomew County, IN: 4.82 m/s, 11,341 kWh, payback 52 years (23 mi)
- Marion County, IN: 5.8 m/s, 18,226 kWh, payback 32 years (26 mi)
Sun versus wind in Shelby County
Shelby County gets 3.99 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,165 kWh a year; one kW of the turbine above makes 1,662. 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.