Standby vs. Portable Generator: Which Is Right for Your House?

A standby generator is permanently installed outside the house, wired in through an automatic transfer switch, and runs on your home's natural gas or propane, so it starts by itself when the power goes out, whether or not you're home. A portable generator costs much less up front, but you wheel it out, start it, and refuel it yourself, and it powers only what you plug into it unless an electrician installs a transfer switch or interlock kit. Pick a standby if outages are frequent or long, someone relies on powered medical equipment, or you're often away. Pick a portable, or a battery power station, if outages are occasional and you're watching the budget.

Either way, the generator itself runs outdoors only. A portable stays at least 20 feet from the house, and a standby is placed by its installer to the manufacturer's clearances and local code. If you've decided on a portable, our best portable generators guide has the picks, the hookup options, and how to size one.

Standby vs. Portable at a Glance

Which One Should You Get?

A standby makes sense if

• Outages are frequent or long. A standby runs on the home's natural gas or propane, and Briggs & Stratton says the fuel is connected at all times, so no refueling is required. With a portable, Kohler notes, you go outside to refuel every few hours, which isn't safe in harsh weather.
• Someone depends on power. Ready.gov tells households to have alternate plans for power-dependent medical devices and refrigerated medicines. A standby takes over on its own, without anyone having to set up and start a generator.
• You're often away, or no one can handle a generator. Kohler says a standby starts automatically whether you're home or away, so the sump pump, furnace, and fridge keep running while you're gone.
• You want the whole house on, central air included. Generac says a standby can restore power to the entire home, depending on the model; a portable is generally better suited to devices and smaller appliances.

A portable (or power station) makes sense if

• Outages are occasional and short, and you'll be home to run it. Generac calls a portable a much smaller upfront investment than a standby.
• You need the essentials, not everything: the fridge, the sump pump, some lights, phones, and, through an electrician-installed transfer switch or interlock, the furnace or well pump. Our portable generator guide covers which models fit which job.
• You rent, live in a condo, or have tight space, where Generac says a portable is the better fit. You still need an outdoor spot at least 20 feet from the house; if you don't have one, use a battery power station instead.

How Much Power You Need

Size comes before type. Kohler puts most portables at 1 to 10 kW. Champion says home standby units run from 8,500 to more than 26,000 watts. If your must-run list fits a portable, you may not need a standby at all; if it includes central air, an electric range, or an electric water heater, a portable usually can't run it all at once.

Our generator size calculator adds up the running and starting watts for the things you tick, and tells you whether the total fits a portable or points to a standby.

Generator Safety: The Rules for Both

Portables: outdoors only, at least 20 feet away

The CPSC says never to use a portable generator inside a home, garage, basement, crawlspace, or shed, or similar area, even when using fans or opening doors and windows for ventilation: deadly carbon monoxide can build up quickly and linger for hours after the generator shuts off. Run it outdoors only, at least 20 feet from homes and buildings, with the exhaust directed away from windows, doors, and vents. Honda's owner's manual adds never to run a generator near open doors, windows, or vents, so keep the ones nearest the generator closed.

Connecting to the house: a transfer switch or interlock, never an outlet

To run hardwired circuits like the furnace or well pump from a portable, the generator has to feed the house through a device that keeps it isolated from the utility lines. Champion describes the two options: a manual transfer switch, wired to a weatherproof inlet box on an outside wall, or an interlock kit mounted on the main panel. OSHA says never to connect a generator to a building's wiring unless a qualified electrician has installed it with a transfer switch, because a direct connection can energize utility lines for great distances and electrocute utility workers.

Never plug a generator into a wall outlet to power the house. The CPSC calls this backfeeding: it's extremely dangerous, puts utility workers and neighbors on the same transformer at risk of electrocution, and bypasses some of your home's built-in circuit protection.

Standbys: the installer follows the clearance rules

A standby makes carbon monoxide too, so where it sits matters. Generac lists clearances based on NFPA 37: 5 feet from openings in the wall such as operable windows, doors, vents, and window wells; 5 feet of open space above the unit; and 3 feet at the front and both ends. Only Generac models marked with the SwRI logo may sit as close as 18 inches from the wall at the back; units without it go 5 feet from combustible materials and 3 feet from non-combustible ones. Generac says local codes take precedence, never to install a unit under a wooden deck, and that even a unit installed to these rules may still let CO into the house, so it may need to go farther away. Other brands set their own clearances in the installation manual, and your installer follows the manual and local code.

CO alarms on every level

With either kind of generator, the CPSC says to install working CO alarms, battery-operated or with battery backup, on every level of the home and outside sleeping areas, and to test them monthly. Our smoke and CO alarm guide covers which to buy, and if one sounds, see carbon monoxide alarm going off.

Installing a Standby Generator

A standby isn't a weekend project. Generac says installation involves plumbing and electrical work that should be done by experienced professionals, and Briggs & Stratton says the initial installation is done by a licensed electrician. Expect:

• A site visit. The dealer picks a stable, well-drained spot with room for maintenance access, and Generac says placing it near the gas line and electric meter keeps the installation simpler.
• A permit. Generac says preparation takes weeks, including obtaining a permit, and Champion notes local authorities often require permits for generator installations.
• The install. The crew prepares the pad, often a concrete slab or pea gravel, connects the fuel line, and installs the automatic transfer switch next to your main breaker box. Generac says its standby generators are designed for an automatic transfer switch, not a manual one, selected and installed by a qualified electrician.
• A test. Before the job is done, Generac says the dealer simulates an outage to confirm the system works.

Maintenance: What Each One Needs

Standby

A standby exercises itself: it starts on a schedule, runs a short self-test, and shuts off. Generac says the exercise can be set weekly, biweekly, or monthly depending on the control panel, runs only when the unit is left in Auto, and can't be turned off because it keeps vital engine parts lubricated.

Oil changes are on a schedule too. For its home standby units, Generac calls for break-in maintenance at 25 hours, then a new oil and filter every 200 hours of run time, every 100 hours in very hot or cold weather, and at least every 2 years regardless of hours, along with yearly battery, fuel-leak, and water-intrusion checks. Generac says you can do the owner's-manual tasks yourself or use a certified service dealer; Briggs & Stratton recommends a professional technician for standby maintenance and repairs. Your model's manual sets the actual schedule.

Portable

Gasoline goes stale. Honda's manual says it can deteriorate in as little as 30 days, and Champion says to add fuel stabilizer if fuel will sit in the tank more than 30 days. Champion also recommends running the generator every month under a real load for 15 to 20 minutes, outdoors and at least 20 feet from the house like any other run, never in the garage. Change the oil on your manual's schedule.

Battery Power Stations: The Only Indoor Option

Every gas, propane, or natural gas generator makes carbon monoxide, so none of them runs inside. If you need power indoors, for a CPAP beside the bed, the fridge, phones, and lights, the answer is a battery power station: it burns nothing and makes no CO. The trade-off is stored energy: it runs until the battery is empty, then needs recharging from the wall, solar panels, or a generator running outside. It can't run a hardwired furnace or well pump on its own. Our best portable power stations guide compares sizes and explains run time.

Frequently Asked Questions

Is a standby generator worth it?

It is if your outages are frequent or long, someone in the house depends on powered medical equipment, or the house has to keep running while you're away. It costs several times more installed than a portable, so for occasional short outages a portable or a battery power station usually does the job. Our generator size calculator shows whether your must-run list fits a portable.

Can a portable generator power my whole house?

Usually not all at once. Through an electrician-installed transfer switch or interlock, a large portable can run a chosen set of circuits, such as the fridge, sump or well pump, furnace, and some lights. Generac says a portable's output is generally better suited to devices and smaller appliances, while a standby can power the whole house, depending on the model. See best portable generators for models that handle the essentials.

How far from the house does a generator need to be?

A portable runs outdoors only, at least 20 feet from the house, with the exhaust pointed away from windows, doors, and vents (CPSC), and never in a garage, even with the door open. A standby sits closer because it's installed to the manufacturer's clearances; Generac's, based on NFPA 37, keep it 5 feet from windows, doors, and vents, and local code can require more.

Do I need a transfer switch for a portable generator?

Not to plug appliances directly into it with outdoor-rated extension cords. To power anything wired into the house, like the furnace or a well pump, yes: a transfer switch or interlock kit installed by a licensed electrician (OSHA, Champion). Never backfeed through a wall outlet.

The Bottom Line

A standby generator is the hands-off choice: it's permanently installed, runs on your gas or propane, and switches on by itself, but it costs several times more installed and needs a professional install, a permit, and scheduled maintenance. A portable costs far less and covers the essentials if you're home to run it, outdoors at least 20 feet from the house, through an electrician-installed transfer switch or interlock for house circuits. For power inside the house, add a battery power station. Size your list in the generator size calculator, and if a portable fits, start with our best portable generators guide.

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