Portable gasoline-powered generators are one way to get backup power, though the electricity they provide is limited, they can be a hassle to use—you have to have a transfer switch installed to run direct-wired appliances such as your heating or cooling system run extension cords in and out of your house for plug-in fixtures—and they pose a very real safety threat if you don't use them properly. "With a portable generator, you might have to have run cords, store gas, and stabilize the gas so you don't gum up the carburetor, says Richard Buttner, of NoOutage.com, which specializes in backup-power systems.
Stationary generators provide much more power than portable units (models we tested produced 6,000 to 12,000 watts) and are easier to use, but they're more expensive. The Kohler 12RESL that topped our ratings costs $3,700 uninstalled. Our generator ratings (available to subscribers) cover small and midsized portable units and stationary models.
A transfer switch lets you plug any generator directly into select critical circuits in your home's electrical panel box and is the only way to safely power a central heating or cooling system and to route power to wall outlets. A manual switch costs about $500 installed; an automatic version runs about $1,000. We recommend you install a transfer switch when you get a generator.
"We're selling a lot more transfer switches now. It seems people have bought portable generators but are trying to make use of them in a more easier way," says Buttner. He adds that compact panel-interlock switches, which install directly onto an electrical panel box and require less wiring than a full-sized transfer switch, cost about $150 uninstalled.
Gas-powered portable generators we reviewed can use 12 to 18 gallons of gasoline a day when heavily loaded. You'll welcome the power they provide during an emergency, but don't forget about fuel storage since gas stations in your area might not be able to pump fuel during a power outage. One portable generator we tested, the $2,000 Northstar 8000TFG, can run off of a liquid-propane tank that offers several days' supply or off a natural-gas line.
Backup systems that use wind or solar power to charge banks of batteries are another option. But, says Buttner, "After an outage, you don't know if the wind is going to be blowing or the sun shining if you need it. Ideally, you'd want both a wind and a solar-based system, but that and the need for batteries greatly increases the overall cost."
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