Wind Turbine Payback in New Castle County, DE
Wind turbine payback in New Castle 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 New Castle County, DE averages 5.23 m/s (11.7 mph). A 10 kW turbine there would make about 14,116 kWh a year, worth $2,538 at DE's 17.98¢/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 New Castle County
A home turbine is not worth buying for savings in New Castle County unless your spot is far windier than the county average, 7.1 m/s at the hub against 5.23 m/s here. Per kW, solar panels would make about 1,188 kWh a year here against the turbine's 1,412, so get a solar quote first.
What would have to change
- Power would have to cost 35¢/kWh, 2.0 times what DE pays now.
- Or the average wind at the hub would have to be 7.1 m/s instead of 5.23. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of DE
New Castle County is the 1,360th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in DE is Sussex County at 5.87 m/s, payback 30 years.
Month by month in New Castle County
March is the strongest month here, at 6.07 m/s and about 1,719 kWh. August is the weakest, 4.00 m/s and 557 kWh, so the best month makes 3.1 times the worst. November to March brings in 55% of the year's output in New Castle County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.99 m/s | 1,669 kWh | $300 |
| February | 6.13 m/s | 1,583 kWh | $285 |
| March | 6.07 m/s | 1,719 kWh | $309 |
| April | 5.88 m/s | 1,546 kWh | $278 |
| May | 4.93 m/s | 1,024 kWh | $184 |
| June | 4.51 m/s | 771 kWh | $139 |
| July | 4.08 m/s | 595 kWh | $107 |
| August | 4.00 m/s | 557 kWh | $100 |
| September | 4.52 m/s | 779 kWh | $140 |
| October | 5.32 m/s | 1,256 kWh | $226 |
| November | 5.62 m/s | 1,392 kWh | $250 |
| December | 5.78 m/s | 1,537 kWh | $276 |
What a taller tower would buy
Measured at 10 m the wind in New Castle County averages 3.97 m/s; at 50 m it is 5.94 m/s. That gives a shear exponent of 0.250, typical of ordinary open country. Going from 20 m to 50 m takes output from 10,723 to 19,260 kWh a year, 80% 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 | 4.72 m/s | 10,723 kWh | 52 years |
| 30 m | 5.23 m/s | 14,101 kWh | 39 years |
| 40 m | 5.62 m/s | 16,891 kWh | 33 years |
| 50 m | 5.94 m/s | 19,260 kWh | 29 years |
Counties around New Castle County
2 of the 6 closest counties are windier at turbine height; the windiest, Gloucester County, averages 5.8 m/s.
- Salem County, NJ: 5.23 m/s, 14,116 kWh, payback 29 years (15 mi)
- Cecil County, MD: 4.83 m/s, 11,407 kWh, payback 41 years (16 mi)
- Delaware County, PA: 3.92 m/s, 6,182 kWh, payback 77 years (27 mi)
- Chester County, PA: 3.92 m/s, 6,182 kWh, payback 77 years (28 mi)
- Gloucester County, NJ: 5.8 m/s, 18,226 kWh, payback 23 years (28 mi)
- Cumberland County, NJ: 5.8 m/s, 18,226 kWh, payback 23 years (33 mi)
Sun versus wind in New Castle County
New Castle County gets 4.07 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,188 kWh a year; one kW of the turbine above makes 1,412. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.2 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.