Generator or Battery Backup: Which Type of Home Backup Power Do I Need?
Three different approaches to home backup power, what each one asks of your house, and the questions that decide which is worth researching further.
Backup power does not mean the same thing in every house. Some homes need a permanently installed fuel-powered standby generator, some are better served by a whole-home or essential-load battery system, and some only need portable power for a short list of essentials. Start with what has to stay on, how much of the house you want covered, how long you want to be prepared for, and how you want the system to behave when the power goes out.
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Visitor understands the three backup approaches and which one suits their loads, coverage and outage expectations.
Start with the house, not the equipment
Every backup decision comes back to four questions: what has to keep running, how much of the house you want covered, how long you want to be prepared for, and how you want the system to behave when an outage starts. Answer those first and the equipment question becomes much narrower.
There are three broad approaches, and they suit different households rather than sitting on a single scale from worse to better.
The three approaches
Fuel-powered standby generator
A permanently installed unit that runs on a fuel source such as natural gas or propane. When it is properly installed and configured, it can respond to a utility outage automatically and supply backup power through the home's electrical system. What it can support depends on how it was sized. Plan around the fuel you actually have available, the outage length you are preparing for, the installation itself, the noise while it runs, and routine maintenance.
Whole-home battery backup
A battery system stores electricity rather than producing it by burning fuel at the house. Properly installed and configured whole-home battery systems can also detect a grid outage automatically, isolate the home from the utility grid as required, and move supported household loads onto battery power. There is no combustion at the house and these systems are generally quiet.
Portable backup power
A portable unit is not a permanently installed whole-home system and is not intended to behave like one. It suits households whose goal is to keep a short list of essentials going: refrigeration, some lighting, internet and network equipment, phones and electronics, and selected small appliances or equipment.
Battery sizing without the engineering
Two numbers do most of the work. Kilowatts (kW) relate to how much power a system can deliver at a given moment, which is what determines whether it can run the loads you switch on. Kilowatt-hours (kWh) relate to how much energy is stored, which helps determine how long that stored energy can support those loads.
Runtime therefore depends on both the system's capacity and what your household is actually running, so no single figure applies to every home. Many systems can be expanded with additional battery capacity, and battery systems may be paired with solar. A properly designed solar and battery system may recharge during an extended outage, depending on how the system is configured and how much sunlight is available.
Five questions to ask yourself
These are the questions worth answering before you compare any specific system. Your answers point to which approach deserves further research.
- What absolutely needs to stay powered?
- Do I want essential-load backup or broader whole-home coverage?
- How long do I want to be prepared for an outage?
- Do I have natural gas or propane available?
- Do I have solar, or might I want solar as part of a future battery system?
Where to go from here
There is no winner among these three approaches. A standby generator, a whole-home battery system and portable power each suit different priorities, homes, load lists, outage expectations, fuel availability, installation situations and coverage goals.
If you are leaning toward a generator, What Size Home Backup Power System Do I Actually Need? covers sizing for both generators and battery systems. If you are not yet sure what needs backing up, What Should I Actually Power During an Outage? is the better starting point. When you are ready to look at real systems, the options on the Home Power & Technology page are grouped by approach rather than ranked.
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What Size Home Backup Power System Do I Actually Need?
Square footage is the wrong starting point. Start from the loads you actually care about, then decide between a fuel-powered standby generator and a whole-home battery system.
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What Should I Actually Power During an Outage?
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