What is a home standby generator?

A home standby generator is a permanently installed backup power system that turns on automatically during a utility outage and powers selected circuits or your whole home. It is installed outside, similar to a central air conditioner, and runs on natural gas (NG) or liquid propane (LP).

How it works

• The generator monitors utility power. When an outage is detected, it starts automatically and an automatic transfer switch (ATS) moves your home’s electrical load to generator power within seconds.
• When utility power returns, the ATS transfers the load back to utility and the generator shuts down.

For a visual overview, see How Home Standby Generators Work.

What it can do

• Provide automatic, hands-off backup power for essential circuits or your entire home.
• Run for extended periods during outages with proper maintenance and fuel supply. See How long will my home standby generator run?.

What it can’t do

• Replace your utility as the primary power source. See Can my home standby generator be used as the primary source of power?.
• Power life‑saving medical equipment. See Considerations for using home standby generators to power medical equipment.

Fuel and runtime basics

• Fuel types: Home standby generators operate on natural gas (NG) or liquid propane (LP). NG is piped fuel from a utility, so there is no refueling; LP is propane stored in a tank on your property.
• Fuel use depends on generator size and load. See How much fuel does my home standby generator use?.
• If you use LP, monitoring tank level helps prevent unexpected shutdowns. See the Fuel Monitor FAQ and How long will my home standby generator run?.
• Some models allow converting between fuel sources. See Can a Generator Be Converted for a Different Fuel Type?.

Key components

• Generator – the engine‑driven unit that produces electricity: What Types of Engines Does Generac Use in Their Home Standby Generators?.
• Automatic Transfer Switch (ATS) – safely switches your home’s load between utility and generator power: What Is an Automatic Transfer Switch (ATS)?.
• Control panel – manages automatic operation and provides testing/exercise and alerts: What Functionality & Commands Does Each Generator Controller Support?.
• Mobile Link – connected app that provides monitoring of your home backup generator: Mobile Link support.

Installation and placement

• Must be installed outdoors on an approved surface and in accordance with local codes and clearance requirements. See Clearance requirements for basic information. Always follow local codes when performing a standby generator installation.
• Approved mounting surfaces include compacted pea gravel/crushed stone, a composite pad, or a concrete base pad. See What surfaces can I install my home standby generator on?.
• Dimensions vary by model. See Home standby generator dimensions.

Note: For site evaluation and sizing, use the Standby Generator Solution Finder or contact a local dealer via the dealer locator.

Operation and maintenance

• Generators run automatically when set to AUTO. For safe manual shutdowns during an outage, see Shutting the generator down during an outage.
• Follow the service schedule for oil and oil filter changes, battery checks, and inspections. See Home standby generator maintenance and Charging system overview.

When to consider a home standby generator

• Frequent or prolonged outages.
• Backing up essential loads, sump pumps, refrigeration, heating/cooling, or work‑from‑home power needs.
• Desire for whole‑home or seamless backup versus portable solutions. See Portable vs. home standby comparison.

Home standby vs. portable generators

Both options provide backup power, but they differ in how they install, start, fuel, and support your home’s loads. Use the side‑by‑side below to decide which fits your needs.

Feature	Home standby generator	Portable generator
Installation	Permanently installed outdoors with an automatic transfer switch (ATS); requires licensed electrical/gas work and permitting.	No permanent install; may connect via a manual transfer switch or selected appliances with cords when used per local codes.
Start & transfer	Fully automatic—detects an outage, starts, and powers circuits or whole home within seconds (learn more).	Manual start required; transfer power via a manual transfer switch or extension cords when used per local codes.
Fuel	NG or LP from utility/tank; no manual refueling. Fuel use.	Typically gasoline, diesel, or LP; manual refueling required.
Noise & placement	Installed outside permanently and sized/placed to meet codes and clearances.	Operate only outdoors away from doors and windows; see How loud is my portable generator?.
CO safety	Installed outdoors; follow local codes and detector guidance.	CO = carbon monoxide, a colorless, odorless, poisonous gas. Never run a portable generator indoors or in enclosed spaces.

See also

• How long will my home standby generator run?
• How much fuel does my home standby generator use?
• Can my generator be used as primary power?
• Clearance requirements for installation
• Home standby generator maintenance
• Fuel Monitor FAQ