Most ordinary grid-tied solar systems do not keep a home powered during a utility outage. To provide backup, a system needs equipment and controls designed for operation while safely separated from the grid. Panels on the roof alone are not a backup-power plan.

For homeowners considering outages or planned shutoffs in Southern California, the starting point is a list of things you want to keep running. That list is more useful than choosing a battery by brand or headline capacity.

Why solar can shut down when the sun is out

A conventional grid-connected system is designed to stop supplying power when the grid fails. SCE describes this behavior in its solar maintenance guidance. A backup design must manage the transition and isolate the home appropriately. Ask the installer to explain the outage configuration in writing.

A battery installation is not automatically a backup installation

Energy storage can be configured for different purposes. Some designs focus on shifting energy use while the grid is available. Others include backup equipment and selected circuits. As one manufacturer example, Tesla documents both backup and non-backup configurations for certain systems. Confirm the exact equipment and configuration in your own proposal.

Request a clear answer to three questions: Does this system operate during an outage? Which circuits receive power? Can the solar array recharge the battery while the utility is down? Do not infer the answers from the presence of a battery icon in a sales presentation.

Battery capacity and power answer different questions

Kilowatt-hours (kWh) describe stored energy. Kilowatts (kW) describe the rate at which equipment can supply power. A design can have enough energy for several hours yet lack the power needed to start a particular appliance. The Department of Energy’s storage overview explains the distinction between storage capacity and power.

For an arithmetic example, suppose 8 kWh is available for backup after your reserve and operating limits. At an average 0.5 kW load, 8 ÷ 0.5 equals 16 hours. At 2 kW, the same calculation gives 4 hours. These are simplified examples, not product-runtime promises; losses, changing appliance use, temperature, and system limits affect actual performance.

Make an essential-load list before sizing

• Refrigerator and freezer: identify their actual consumption and starting needs.
• Internet equipment, phones, and a few lights: list the devices you need.
• Garage doors and gates: ask whether their circuits are included.
• Air conditioning, pumps, or electric cooking: ask for a specific power and runtime assessment.
• Any critical equipment: discuss its requirements and an appropriate contingency plan with the relevant professional.

Ask the designer to distinguish equipment that can run individually from equipment that can run simultaneously. “Whole-home backup” also needs a practical explanation of load management. It does not establish that every appliance can run together for an unlimited period.

Balance everyday use with outage reserves

A household using stored energy every evening may have less available when an unexpected outage begins. Ask how the reserve setting works and what happens during extended cloudy weather. For a multiday outage, request a scenario that shows daytime generation, essential loads, and overnight energy needs together.

Also identify who will commission the system, demonstrate the app, and provide support. Before accepting the project, ask for a walkthrough of the backed-up circuits and the installer’s approved operating instructions.

Frequently asked questions

Can I add a battery to existing solar?

Sometimes, but compatibility and the existing installation matter. Have a qualified installer review the inverter, electrical equipment, utility requirements, and proposed backup configuration.

Can a battery run central air conditioning?

Possibly. The answer depends on the air conditioner’s starting and running demand, other simultaneous loads, and the system’s power rating. Ask for a written design assessment.

Will solar recharge a battery during an outage?

Only if the installed system supports that operation under the conditions at the time. Confirm this feature for the proposed design, along with any operating limits.

Explore our solar and battery options or visit the FAQ page for related questions.

Want to understand the options for your property? Request a free solar assessment. Los Angeles Solar Advisory helps homeowners in Los Angeles, Riverside, and Ventura counties explore solar options through consultations representing Axia by Qcells. Your proposal should reflect your home, utility, and contract terms.