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Home Backup Generator Buyer’s Guide: How to Choose the Right One for Your Home

Home Generator in Phoenix

Want to make sure your home always has power, even during blackouts?

You need a backup generator.

But there are so many options. How do you choose the right one? Let us show you.

Step 1: Know your options: standby vs. portable

There are 2 basic kinds of home generators: portable and standby. The right one for you depends on what you want out of it.

Portable generators

A portable generator, as its name implies, can be moved around. It’s usually on wheels, although with some models the wheels are sold separately. Portable generators are generally less powerful than standby generators but also less expensive.


  • Less expensive. Portable generators range from a few hundred dollars to a couple thousand.
  • Can power a couple appliances. If you only want to keep a couple small appliances (like your home computer network) up and running, a portable generator could handle it.
  • No installation costs. You don’t necessarily need a professional to install a portable generator.


  • Fuel storage. Most portable generators use gasoline. That means you have to have gas on hand and ready in case of emergency. And gas storage has its own set of issues.
  • Short runtime. Since portable generators have a fuel tank that must be filled, you might run out of fuel before the power is restored to your home.
  • Lots of extension cords. To run your portable generator safely, it’ll need to be outside and away from your home. So you’ll need to run extension cords to each appliance you want to power.
  • Lower capacity. Portable generators generally produce less electricity than standby generators. And a portable generator won’t be able to power your AC or your entire home.

Standby generators

Standby generators are permanent fixtures outside your house, similar to a central AC unit. They’re mounted on a concrete pad and automatically provide power to your home or just the most essential items when the power goes out. Standby generators may be the right choice when you can never afford to be without power.


  • Automatic operation. When the power goes out, standby generators kick in automatically  (whether you’re home or away) with almost no downtime. And they’ll run until the power is restored to your home.
  • No extension cords. Standby generators tie directly into your electrical panel, so you won’t have to run power cords to individual appliances to keep them running.
  • No fuel tank to fill. Standby generators tie into your natural gas line so you never have to fill them up. If you don’t have natural gas, they can also be run on liquid propane (LP) fuel.
  • Provides more electricity. Standby generators can typically provide much more electricity than portable versions. Some can even power your whole home.
  • Adds value to your home. A standby backup generator can add value to your home if you ever sell.


  • More expensive. An installed a standby generator can cost anywhere from $6,000 to $25,000. The size of the generator, where its placed, the amount of materials required and the installation of the natural gas or LP fuel source all affect the final price.
  • Requires professional installation. Because you’re hooking into your home’s electrical system you’ll need a professional to install it.

Step 2: Determine the right generator size

A home backup generator size is measured in watts. A watt is a measure of electricity. You must select a generator that can produce the amount of electricity (watts) to power the appliances, outlets and lights on the circuits you want to backup.

But before you determine the wattage you need in a backup generator, you must decide what you want to backup – just the essential circuits or your entire home.

Backing up only essential circuits

Most homeowners in Arizona choose to only backup essential circuits in their home. This allows them to save money by purchasing a smaller generator while still having all the essential appliances (refrigerator, AC, etc.) working during a power outage.

To determine the generator size you need to backup just your essential circuits, figure out the wattages of the appliances you want backed up.

For example, let’s say you want your generator to power a:

  • Central air conditioner that uses 5000 watts
  • 40-gallon electric water heater that uses 5000 watts
  • Refrigerator that uses 425 watts
  • Computer and monitor that uses 125 watts

Then you’ll need a generator that can produce 10550 watts, or around 11 kilowatts (1 kilowatt=1000 watts).

Note: These are approximate numbers used for illustration purposes. If you need help calculating the size generator you should get, contact us.

Backing up your entire home

If you want your entire home to function during a power outage, you can get a whole-home standby generator.

To determine the size generator you need to backup your entire home, you’ll still want to add up the wattages of your appliances. Except instead of only computing a few circuits worth, you’ll want to add up your whole home.

Generac has a great calculator for sizing your generator. However, it’s only a starting point, and you should still get help from an electrician in Phoenix.

A note on backing up multiple air conditioners

Backing up multiple air conditioners with a generator has some complications. Two (or more) air conditioners starting simultaneously will overload even the most powerful generators.

Manufacturers have figured out a way around this with what’s called AC shedding. Basically, this technology prevents both air conditioners from starting at the same time. One air conditioner will be ‘locked out’ by the generator until the first AC has already started.

Get your Phoenix area home sized by a professional electrician

Need help selecting a backup or standby generator in the Phoenix area? Contact George Brazil Plumbing & Electrical for help.

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