A friend of mine, a physicist, gave me an interesting idea:
Buy a good strong power inverter, like 1000W Schumacher,
and hook it to the 12-V battery. Put the keys in the ignition.
The power is enough to drive your refrigerator, LED lights and laptop and cell phones chargers during emergency blackout.
How it works: The 12-V battery takes electricity from the big battery.
When the Li battery drops under min level, engine starts and recharges it.
Then engine shuts down and waits till the next power drop down.
Pros: No need to buy, store and maintain a generator from HomeDepot.
1000 W power inverter is the size of the shoe box.
The car you drive every day is ready to give you power anytime.
No rusty or clogged carburetor.
Prius will turn on 10-15 min each hour or so. Will not produce unused electricity all the time, only as much as you consume.
Prius is silent. emergency generators are noisy.

However, another friend of mine, car specialist and engineer, said it will not work with Prius, but perhaps will work with Volt. His argument, Prius will only generate electricity for as long as it moves.

He is right but for the wrong reason.

The Prius will indeed TRY to keep the 12 V battery charged as long as it is ON, that is in the READY mode and in Park and not Neutral.

HOWEVER......to produce 1KW of power, that would require about 85 AMPS out of the 12 V battery and it's charging converter. Neither the battery or the charging converter are designed with that kind of capacity.

It would work......for about 3 minutes.

I seriously doubt that the Volt has the capacity either.

Dear Easy Rider,
Thank you for your quick answer.
The 1000 W inverter is a bit overkill, but we should have extra capacity.
Regular refrigerator is rated at 6.5A, i.e. 700W.
This is only for few seconds, until it reaches the pressure differential.
After that the power consumption drops to 200-300 W.
Correct me, I may be wrong.

Drawing 85 A from a car battery is not a problem, especially a few seconds.
Cranking average car with average battery, current goes to 200-300 A.
For few seconds only, true.
The biggest problem, I think, is how much current can the car produce to refill the 12-V battery.

That's why, I insist that only LED lights, laptop and cell phone chargers should be plugged in. The big consumers are AC, water heater, dryer, etc. However, during emergency, we can go filthy stinky and unshaven for few days. Hot water is always available on the gas grill.
Most important, to save the food from spoiling.

PS: I did my home work. This is an old idea.
There are places over the internet about this.
12-V battery is not involved.
Plug the big battery to a big inverter. 2-3 or 5 kW, depending how much you plan to draw.
It will save money compared to standard generators, because the Prius engine is much more efficient than the gas generator honda or briggs+stratton. And also, because you only generate what you need. And it is silent!

You are overlooking the fact that the Prius does NOT use the 12 V battery and a conventional starter to actually start the engine. Because of that, the battery is MUCH smaller than in a conventional car; about half the capacity of some cars.

And because there is no huge current spike required.....ever.....there is a smaller battery AND a charging system with a much lower capacity. Your proposal is NOT practical. But if you do try it out please let us know how it works.....or doesn't.

And as far as your other proposal........there are dangers when tinkering with the HV system, both to YOU and to the car.

I think that screwing around with a ~$25,000 car instead of just buying a ~$3000 generator is just plain stupid.
And......all that just to save a hundred dollars in potentially lost food ?? Really ??

Sounds good, I never thought about this!

So it works as a real generator. But I think it will be a very bad idea to use if for house. I mean 1000 is not that much and it can blow or just give less power to the house, everything depends on the condition of the battery. The idea is pretty good, especially for those people that loves to go camping and they need electricity or for work at contruction or smth else. Btw, you should check the best generator for home of 2020, there you can find the real generators that are able to give power to all the house.