These are the huge permanently installed boxes you sometimes see outside of homes or small businesses. They can power a few essential circuits or the while nine yards and will cost you anywhere from $2,000 to $14,000 plus, according to Electric Generators Direct. You can also pick out generators to power, say 16 circuits with load-shedding of extra power to other circuits. A standby generator should turn-on automatically when power goes out. Many of these run on propane, diesel or natural gas, with gas lines from the gas company. You may need a local permit, and be sure it is sized to your needs. They range from 8 kw to 125 kw, with smaller ones for essential loads about 8 kw to 17 kw. You can also get dual natural gas and propane, which is useful if gas lines are disrupted.

Here’s a good video on how standby generators work.