The generator in the photo is probably larger than you need to run your house, and it also probably costs more than a nice car. But you can rent one like that, for a reasonable fee, and have it hauled to your house/office/business after an event to supply temporary power. At home, though, a smaller, portable generator can keep the American convenience level high while you wait for the power to be restored after a storm or accidental event. Generators are stocked at your local home store (Orange front, Red and Black front) for as little as 250 US most of the year. But taking that power plant home and connecting it to your house is more involved and requires research and planning.
Connecticut Light and Power requires that portable home generators be connected to your house in compliance with the National Electric Code and its own guidelines. That means a licensed guy like me has to do the work, and the equipment has to be UL listed and approved for the purpose. The importance of all this regulatory protocol is that people die from home generator use and misuse almost as often as they die from disasters.
Major hazards are: Carbon monoxide, emitted in generator exhaust, collects in closed areas seeps down stairs into other areas, and kills people. In the 2006 storm season too many people died after the floods receded because of generator misuse. After carbon monoxide comes electrical shock caused by improper hookups in the presence of water. Electricity and water kill when mingled. And another, no less important hazard from home generators is called “islanding,” when generators feed back to the grid through home distribution panels and ad hoc hookups and send power to the transmission lines. Line workers are endangered by islanding, and there have been too many fatalities. It’s hard for linepersons to guard against some joker starting up a generator while they’re working on a pole. And other homeowners or licensed electricians are also endangered by islanding when work is being done on wiring in storm-damaged homes.
How big a generator do you need? To operate everything in a typical modern American home (air conditioning, cooking, lights, hot water, computers, television, etc.) a round figure would be 10 kw. That’s 10,000 watts. You might do ok with 8 kw.
You might also be fine with a smaller generator and some awareness about what loads you’re using at any one time. With shrewd load management I can run my house on my 5 kw generator, the same one I use to power remote or as yet unconnected construction jobs. We do fine that way. But we have to think about it.
You can have a generator, and you don’t HAVE to hook it up to your house wiring. You can run extension cords to selected loads (fridge, microwave, space heater) and get by ok. And it will be safer. That’s your most cost-effective route, but it’s inconvenient, and probably un-American.