How to Choose
"Decide what you really need to power. If that includes a central air conditioner or an electric dryer or oven, you'll need a larger generator. Here's what else to keep in mind:
Count on a transfer switch. It costs about $500 to $900 installed and connects a portable generator to your home's circuit box as with a stationary model. In addition to eliminating the risk and hassle of extension cords, the switch protects the generator and appliances from damage when grid power returns and keeps the generator from endangering technicians working on the power lines.
Think about the fuel. Most portables use roughly 8 to 22 gallons of gasoline a day, compared with four to eight 20-pound tanks of propane for portable models. (A 250-gallon tank for stationary units can run 8 to 15 days.) Buying and storing lots of fuel before a storm can be unwieldy, although you can pour unused gasoline into your car's gas tank.
Look for smart features. Most of the portable generators in our tests turn themselves off when engine oil is low. And the fuel shutoff on all tested gasoline models lets you run the engine dry to draw gas out of the fuel system to keep it from fouling parts if it degrades during storage..."