using prius to power house electric grid

Yes, and no. Yes, it is capable, but no, there is no ready-made kit. Toyota has set up an experimental house, and other home hobbyists have made encouraging progress tapping into the High Voltage system, but you would have to modify the car yourself, and the modification isn't for the unknowledgeable or the faint-hearted.

As an alternate, some have experimented with getting 500-1000 watts from the 12V system, but that isn't enough to power a house. It may do a few small appliances, or an energy-efficient refrigerator.

Bottom line is, the car is capable, but no one has a robust solution that they are ready to sell you.

I've often advocated Toyota putting a circuit-breaker protected HV tap under the hood behind a locking connector. I could easily take it from there.

 

This issue is addressed exhaustively and entertainingly at http://www.priups.com/ . I sincerely hope that in future model years, Toyota will make this a dealer-installed option.