Choose Home Battery Backup by Load, Runtime and Connection

Back up the equipment you need, not every appliance you own. Consider a UPS for short interruptions to electronics, a portable power station for plug-in essentials, or an installed battery system for household circuits. Then check two separate limits: watts determine what can run; watt-hours determine how long it can run.

If the outage is already underway, disconnect unnecessary loads and check the battery’s charge and output settings. If you depend on powered medical equipment to stay alive, seek emergency services immediately. For backup planning, the FDA’s medical-device outage guidance says to check the device instructions or contact its manufacturer about battery or generator compatibility.

Which kind of battery backup fits?

Your task	System to consider	Main limitation
Keep a computer or network equipment running through a brief interruption	UPS—uninterruptible power supply	Check the exact model’s runtime at your load; VA is not battery capacity
Run selected plug-in appliances without altering house wiring	Portable power station	Outlet voltage, continuous output, motor-starting surge and stored energy
Automatically supply selected household circuits	Installed home battery with backup equipment	Requires professional design, installation and grid isolation
Keep most household loads available	Larger installed system with load management	“Whole-home” connection does not mean unlimited power or days of runtime

Schneider Electric’s UPS guide describes typical home/office UPS runtime as roughly 5–20 minutes, depending on model and load. Smaller loads can run longer; use the manufacturer’s runtime chart rather than a universal minutes claim. Stay within both the UPS’s watt and VA ratings, and use its battery-backed outlets—not surge-only outlets.

For portable-unit comparisons and smaller-battery runtime examples, see choosing a portable power station for home backup.

Installed batteries can charge from the grid or solar; solar is not required to store backup energy. To recharge during a grid outage, however, the battery needs a supported source that remains available. NYSERDA explains grid charging, solar charging and home-storage arrangements.

Size output power before calculating runtime

Write down the essentials, their running watts, starting requirements and required hours. Measure plug-in loads where practical; for hardwired equipment, have the installer determine demand.

Check:

• Continuous output: Can the inverter supply the loads running together?
• Starting surge: Can it start a refrigerator compressor or pump while other loads are operating? Jackery’s refrigerator guidance recommends confirming startup demand with the appliance manufacturer.
• Voltage: A 120-volt outlet cannot directly supply a 240-volt appliance. Check the equipment nameplate and the backup system’s actual output.
• Connection: Plug-in appliances and hardwired household circuits need different arrangements.

Do not substitute an advertised “boost” mode for compatible rated output. For example, the EcoFlow DELTA 2 manual warns that its X-Boost feature is incompatible with equipment that has strict voltage requirements.

For cycling appliances, use energy measured over representative hours—not just compressor-on watts. For a storm-driven pump load, use the separate sump-pump battery sizing guide; pumping duty matters as much as motor wattage.

How much storage does a day of backup require?

Required energy in Wh = average load in W × hours. One kilowatt-hour equals 1,000 watt-hours. Energy capacity is distinct from power output, and storage has conversion losses, as the Department of Energy explains.

These are arithmetic examples, not tested appliance runtimes:

Average combined load	Energy delivered to loads over 24 hours
100 W	2.4 kWh
300 W	7.2 kWh
500 W	12 kWh
1,500 W	36 kWh

At an average 300 W for 24 hours, you need 7.2 kWh delivered to the loads. If you illustrate losses and unavailable energy by assuming that 80% of nominal storage reaches the loads, that means 9 kWh of nominal storage, before a contingency margin. The 80% factor is an example—not a guaranteed efficiency or minimum runtime.

Use model-specific usable-energy data where available. If capacity is already stated as energy delivered at the AC output, do not subtract inverter losses again. Starting charge, reserve settings, battery age, temperature and inverter idle consumption affect available energy. The Goal Zero Yeti 1000/1500 manual, for example, notes that active output ports consume energy even with nothing connected.

To estimate runtime instead, divide energy available to the loads in Wh by their average load in W. Keep the output-power check separate: enough stored energy does not guarantee that the inverter can start or run an appliance.

Connect and test it before the outage

Never feed battery output into a household wall outlet to energize the house. This is the same unsafe backfeeding connection method that the CPSC’s generator safety alert warns can electrocute utility workers and neighbors and bypass household circuit protection.

Plug appliances into the portable unit as instructed. Keep it dry and its ventilation openings clear, following its manual. For household circuits, use manufacturer-supported transfer or islanding equipment installed by a qualified electrician. ESFI recommends professional installation and servicing of energy-storage systems. Ask the installer to identify backed-up circuits, simultaneous-load limits, reserve settings and local approval requirements in writing.

Have the installer demonstrate outage operation for a hardwired system. For a plug-in unit with automatic backup, test compatibility as its manual directs—not just whether it charges. A power station’s emergency-supply mode may briefly interrupt power: the DELTA 2 manual specifies switching within 30 milliseconds, not zero, and says not to connect equipment requiring zero-interruption backup. It also warns that idle-output timeout settings can shut off power to cycling loads such as refrigerators; for that use, it directs owners to set AC timeout to “never” and regularly check battery level.

Finally, plan for depletion. Ordinary grid-connected rooftop solar generally shuts down during an outage; DOE explains the need for a properly configured inverter and storage system for backup operation. Confirm that solar can recharge your particular system while isolated from the grid, and plan for poor production during storms. Set a departure or alternate-power trigger before the battery reaches empty.