Originally posted: Sept 2013, consumerreports.org/cro/generators/buying-guide.htm

Types

Knowing what you’re powering is the first step to choosing the right generator. Here are the types of generators and their pros and cons.

Portable generators

These small and midsized models typically put out anywhere from 3,000 to 8,500 watts. They cost from $400 to $1,000 and are adequate for many homes, which is why they’re the biggest sellers. Most portables run only on gasoline, but some can also use liquid propane or connect to a natural gas line.

Pros: They cost the least and are relatively easy to move and store. And they’re adequate for powering common plug-in appliances and lights.

Cons: Portables don’t provide nearly enough power for heavy drains like central air conditioning. And for most, you’ll have to store large quantities of gasoline, a hazardous fuel.

Stationary generators

These large models mount permanently outside the house and are growing in popularity. Their roughly 5,000 to 15,000 watts let the largest power an entire house, including central heat and air conditioning.

Pros: Besides providing plenty of watts, stationary generators can power a bevy of hardwired items, eliminating the hassle and risk of running power cords. Most run on either propane or natural gas, eliminating the risks of pouring and storing gasoline.

Cons: All of that power and convenience comes at a price ($5,000 to $10,000 for the largest models). Stationary generators also require professional installation.