[elihu]

There's two ways to power your house off your car battery. You could have your car act as a mobile electrical outlet that you can run extension cords off of to plug things into, or you could have it tie in directly with the wiring of the house so all your electrical outlets work.

The former is pretty straightforward. The latter would need a lot of electrical upgrades to the house. (I'd expect you'd need to do about the same thing that people do when they get solar, which is to replace the meter with something that can measure power flows in both directions, and is smart enough to disconnect the solar panels from upstream power when the power goes out, so you don't electrocute people trying to fix the power lines. If you don't have a local battery, that means basically turning the solar system off in a power failure.)

If you aren't planning on selling storage capacity to your local utility, maybe all you really need is an automatic shutoff switch to disconnect your house from the grid when the power goes out.

Either way you'd need some sort of power inverter to convert DC to AC. That could be built into the car, or it could be attached to the house.