What Size Wind Turbine?
Good question!
If we assume a wind turbine efficiency of 50% and that a household can demand up to about 13 kW, we can calculate the wind turbine diameter. Let us assume a dry air density of 1.225 kg/m3, which corresponds to a temperature of 15oC and pressure of 101.325 kPa and wind velocity of 5 m/s.
An equation from this page will be used:

That is a large turbine! A little good news might be that if the wind velocity were assumed to be 10 m/s, the turbine diameter drops to 7.35 m.
I undertook to estimate my peak power consumption to compare with the 13 kW assumption above.
| Appliance | Watts | Note |
| Oil Furnace | 3000 | guess |
| Oven | 2,000 | guess |
| Refrigerator | 725 | |
| 2 Computers | 540 | |
| Coffee Maker | 1,000 | |
| Water Heater | 3,000 | |
| Clothes Washer | 500 | |
| Clothes Dryer | 3,000 | |
| Truck Engine Block Heater | 1,000 | guess |
| Stuff I did not include | 1,000 | |
| TOTAL PEAK DEMAND | 15,765 |
So the 13 kW rule of thumb is not bad, assuming that 3,000 W of total demand is not active at any given time. Note that this is a winter time list - the oil furnace and truck engine block heater would lower the peak demand to 12,785 W in warm weather. The oven, clothes washer and clothes dryer could be scheduled to run at different times further reducing the peak demand another 2,500 W to 10,285 W. The refrigerator and coffee maker could also be made to not run simultaneously - another 725 W peak demand reduction to 9,560 W.
Assuming a 10,000 W peak demand for my house and redoing the calculation above, I would still need an 18 m diameter turbine at wind speed of 5 m/s or a 5 m turbine at wind speed of 10 m/s. Wind power is not looking so attractive .... unless we could store the continuous output. Realistically, the furnace might run 10% of the time, the water heater maybe 2% of the time the refrigerator maybe 5% of the time, the laundry appliances maybe 0.7% of the time.... There is actually only about 2,540 W that might be considered continuous but that would still require a nine metre turbine just to power the continuous loads.

