Choosing the Right Backup Generator for Your Home

Updated: Jun. 21, 2024

Don't let severe weather leave you in the dark. An electrician talks generator choices right here.

Springtime in Texas means powerful thunderstorms, and this year has been a doozy. When I moved here a few years ago from Minnesota, my inner electrician talked me into buying a portable generator. I’m glad I did. Just last week, I ran mine for two days after trees toppled power lines all over town. I’ve used generators on construction sites for years, and I’ll never have a home without one.

No matter where you live, the occasional blackout is not unheard of. Florida has hurricanes, California has wildfires, and everyone is facing the prospect of changing weather patterns. Having a secondary way to get power can be a game-changer when faced with the cost of replacing spoiled food, finding a powered place to work, or just staying cool during 100-degree stretches of weather.

When buying a generator, you have two broad choices: a portable model that you stash in your garage or shed and pull out for emergencies or a whole-home version that’s constantly on alert and switches over automatically when the lights go out. Below, I’ll talk about the differences, including price, and what I’ve learned over the years working with these helpful power providers.

What Is a Portable Generator?

Choosing The Right Backup Generator For Your Home Portable Generator IllustrationTMB Studio

A portable generator is a small, mobile power source that converts mechanical energy into electrical energy. You fill it with gasoline or propane and manually start the engine when the power goes out. To run your appliances, you need to either run extension cords from the generator to the individual devices or have an electrician install a manual transfer switch subpanel that allows the generator to power certain important circuits in your home. The first option is the easiest and cheapest.

Basic portable generators start at a few hundred dollars for less than 200 watts of power, but I’d save those for camping trips. For home use, you’ll need a generator that provides thousands of watts. Expect to pay $500 up to $5000 or more, depending on how many things you need to run. To put things in perspective, my 4500-watt dual-fuel generator costs about $1000, and it kept my fridge, window A/C, computer and television (and more) going after last week’s storm.

What Is a Standby Generator?

Choosing The Right Backup Generator For Your Home Standby Generator IllustrationTMB Studio

A standby generator, also called a whole-home generator, automatically senses when the power goes out — you don’t have to do a thing. No dragging it out of the garage after a storm, no storing gasoline or propane. Fuel is stored in an underground tank or supplied by your home’s natural gas. Standby generators are larger than portable generators (7,500 watts to 48,000 watts or more), and they’re more expensive, running anywhere from $5,000 to more than $25,000.

Standby generators need to be professionally installed by a licensed electrician. Some can run your entire house, including central air, kitchen appliances, sump pumps, and other critical power needs simultaneously. They are quieter than portable generators, and you don’t need to worry about running extension cords.

What Size Generator Do I Need?

Generators aren’t cheap, and power outages are temporary. Before running out and buying the biggest (or smallest, for that matter) generator you can find, figure out what you want to run when the electricity’s off. Include essential items like the refrigerator, microwave, sump or well pump if you have one, and if it’s Texas in July, an air conditioner. (If you’re in my old home state of Minnesota, maybe the A/C isn’t as critical.)

Computers and televisions don’t take much juice, but boredom is real, and you might have to work. Include those, too. Then, walk around your house and look for a label on each appliance or device — they have to have one. It will tell you the wattage needed to run it. If you only see amps listed, multiply the amps by 120 volts to get the watts. Write these numbers down and add them up.

Wattage of common appliances

Here’s a broad idea of your appliances’ wattage requirements. Keep in mind that newer appliances will be more efficient than older models, and brands may vary widely.

  • Microwave: 800 to 1,200 watts
  • Refrigerator: 300 to 800 watts
  • Television: 50 to 200 watts
  • Laptop computer: 50 – 100 watts
  • Window air conditioner: 600 to 1,500 watts
  • Sump pump: 800 to 1000 watts

These are the running watts; Appliances with motors, like fridges, air conditioners and sump pumps, will also have starting watts, which is a brief surge that happens when the appliance starts up. To make sure you have enough extra power from your generator to start and run your appliances, multiply the watts by 1.5, and buy at least that size generator.

Running a generator at full capacity will wear it out, so try to keep the load to about 75% or less of its capacity. Getting one that’s a little bigger than you need is better than getting one that’s too small.

Which Generator Is Right For Me?

It’s purely a matter of preference and your individual needs. If your climate is pretty stable, and you rarely need emergency power, a mid-range portable generator is probably fine. They don’t take up much space, and you’ll be happy you have it during an extended outage, however rare. If you think life’s too short to fiddle with extension cords and gallons of gas, and you’re fine making a major investment in your home, a standby generator is for you.

Another consideration is the health and safety of your family. If you have household members with critical medical needs, you can’t afford to worry about powering dialysis equipment, running a CPAP machine or keeping medicines cold in the refrigerator.

If I were building a new home today, I would 100% put in a whole-home standby generator. Down here in the land of frequent storms, they’re extremely common on new residential construction, and I’ve coiled up enough bulky, tangled extension cords at work to last a lifetime. For now, though, a portable generator serves my needs, but my next project is installing a transfer switch subpanel to make my life easier.

If you need any help figuring out what to buy or how to install and run a generator safely, contact a licensed electrician. That’s why we’re here.