I know nothing about wind turbine power generation.
But I would venture a guess to say that 400w is a tiny fraction of the amount of power you'd actually need to make it work. I don't know how many kW of power you use a month, but you'd need to figure that out as a starting point. But yes, if you had enough batteries and wind you could potentially be completely off the grid. But I would guess that most folks that do their own wind power have a moderate battery capacity to get them through lulls (or switching on that A1400-8) but stay connected to the grid, either to back-feed it with wind energy or to draw power from it when they need it.
At one point I read a news article about wind power, and it had online tools where you could plug in your electical usage and location (for wind-energy calculations) and it would spit back how many kW worth of wind turbine power you'd need, and estimated costs for installing it. My electrical bill is between $50 and $150/month (our home is heated by natural gas). When I plugged in the calculations on that site, all I remember is that to get the electricity I'd need it would cost about $15,000 for the mills (I think it was two of X capacity) & power equipment.
If/when we ever move out-of-town to an open area, we'd like to build a home and we would seriously consider doing that. Tacked on to the cost of building, it's not that much. And it'd be pretty cool to be able to generate your own power.
