Do Solar Panels Work During a Power Outage? Check the Backup Design

Solar on the roof does not automatically mean power in the house

The U.S. Department of Energy explains that grid-connected solar generally depends on the grid and is designed to switch off when grid power is lost. The CPUC likewise says most solar systems automatically power down during a shutoff so they do not energize utility lines being handled by repair crews and first responders.

Why the grid-tied shutoff happens, by name

A grid-tied solar panel is a passive DC source — it doesn't "need" electricity to generate, but the inverter that turns that DC into usable AC power needs the grid's own AC signal to synchronize to before it will push power into your house. When the grid goes down, code requires the inverter to stop. This is called anti-islanding, and it's not optional: PG&E's own interconnection requirements state that the utility requires UL1741 SB–certified inverters for new interconnections (effective August 29, 2023) and has incorporated IEEE 1547.1-2020 test procedures into its testing regime for that certification (PG&E, accessed 2026-09-22). The rule exists so a solar-fed circuit can't stay energized and shock a lineworker who thinks the line is dead — it's a safety requirement, not a limitation your installer forgot to design around.

A backup system has to create a safe electrical island

A backup-capable design disconnects the home from the utility grid and establishes a controlled source for the selected circuits. That usually involves compatible controls, an inverter that supports the intended backup mode and stored energy. The equipment list alone is not enough. Ask for a one-line diagram and written description of what happens when grid power fails, at night and when the battery reaches its reserve.

Two ways to actually keep the power on

There are two hardware paths that let a grid-tied system provide power once the grid is down, and they solve different problems.

Battery with a backup gateway. This is the path the rest of this page already covers — a battery and transfer equipment create a controlled island for selected circuits, independent of the grid. It can run through the night and keeps working after dark, which the second option cannot.

An inverter with a secure power outlet. Some grid-tied string inverters include a dedicated outlet that works without a battery. SMA's Sunny Boy line, which uses what SMA calls a Secure Power Supply, is the example most California installers cite: when the grid fails, you flip a switch on the inverter and it feeds one dedicated outlet — up to 2,000 watts (20 amps) — directly from whatever the panels are producing at that moment (SMA America, accessed 2026-09-22). No battery required, typically a $350–$400 install add-on, no 240-volt loads, and it only works while the panels are producing — nothing at night or on a heavily overcast day. A narrow fix (a fridge, a phone, a medical device by day), not whole-home backup.

Choose the loads before choosing battery capacity

Write down the equipment that must stay on: refrigeration, lights, communications, medical devices, well pumps, garage access or heating and cooling. For each load, identify running power, startup demand and daily use. A whole-home label does not show whether every large appliance can operate at once or how long the stored energy lasts.

How long a battery keeps your chosen circuits running depends on the battery's usable capacity, how many circuits you put on it, and how much those circuits draw — there's no single "hours of backup" number that applies to every home, and we won't invent one here. For a sizing method built from your own panel and usage instead of a sales estimate, see how many batteries do I need in California?

Backup proposal checklist

Test the ugly scenarios before signing

Ask the bidder to model a nighttime outage, low-sun days, smoke or shade, simultaneous motor starts and an outage that lasts longer than one day. Compare those results with the household's actual critical loads. No battery lasts a guaranteed number of hours without specifying the load, starting state of charge and energy available during the outage.

PSPS planning is larger than the solar system

California utilities can use a Public Safety Power Shutoff when weather and fire conditions create risk. A PSPS is a deliberate, utility-initiated shutoff during high fire-risk weather — different from an equipment outage, and one solar alone (without a battery or secure-power-outlet inverter) does nothing to prevent. What each major California utility says about it on its own PSPS page, checked September 22, 2026:

None of the three utility PSPS pages recommends a specific backup technology; SDG&E's page notes Community Resource Centers for charging small devices and mentions keeping a generator on hand as an option. Keep utility contact information and alerts current, build a household outage plan and identify a second way to support essential medical or accessibility equipment. The CPUC says customers using electricity-dependent medical devices should plan for an extended outage.

SGIP's Equity Resiliency incentive, for PSPS-affected households

Separate from the general storage incentive on our battery hub, SGIP has an Equity Resiliency budget built for PSPS-affected households. CPUC's SGIP page lists the rate at $1,000 per kWh of installed storage (CPUC, accessed 2026-09-22); the program administrator's budget page says the incentive "could cover as much as 100% of the cost" (SGIP Program Administrator, accessed 2026-09-22). Eligibility needs one condition from each of two groups:

Location or outage history: in a Tier 2 or 3 High Fire-Threat District, or has experienced multiple PSPS events (sources differ slightly on the exact threshold — SGIP's own budget page says two or more PSPS events, or one PSPS plus one wildfire-caused outage since January 1, 2017; PG&E's SGIP page says more than two PSPS events, or five or more Enhanced Powerline Safety Setting outages since 2023).

Household vulnerability: enrolled in a utility medical baseline program, meets low-income criteria, relies on an electric well pump for water, or already qualifies for CARE, ESA, SASH, or DAC-SASH.

Budget availability changes by utility territory and by month, and the CPUC's own page currently shows this budget listed as "available through 2025" — worth confirming directly before anyone counts on it. For the current, per-utility reservation status, see: SGIP battery rebate status in California

Require a real commissioning test

Before final payment, ask the installer to demonstrate the grid-loss transition, identify the backed-up circuits, show the reserve and load controls, and leave written shutdown and restart instructions. Keep the installer, equipment and utility support contacts with the electrical diagram. For the storage decision itself, use the battery and backup guide.

Generator vs. battery, in practice

Both keep the lights on; they aren't the same purchase. A battery is silent, switches over automatically through the gateway described above, and (paired with solar) recharges without fuel. A portable or standby generator runs on gasoline, propane, or natural gas, has to be started and fueled, and produces exhaust — it must run outside, away from doors and windows. SCE offers separate, much smaller rebates for the two smaller devices: $150 for a qualifying portable power station (limit five per address) and $200, or $600 for income-qualified or medical baseline customers, for a qualifying portable generator, for customers in a Tier 2 or 3 High Fire-Threat District (SCE, accessed 2026-09-22). SCE also runs a Critical Care Backup Battery (CCBB) program: free portable backup batteries, with delivery, setup and training provided at no cost, for customers who live in a high fire-risk area, are enrolled in SCE's Medical Baseline Allowance program, and require electrically powered medical equipment (SCE, Critical Care Backup Battery Program, accessed 2026-09-22). No runtime-in-hours figure is stated for either option — it depends on the unit and the load, same as a home battery.