Plug-in solar, batteries and power outages

The short answer: a plug-in kit on its own won't keep your power on in an outage. It has to switch off when the grid goes down, to protect the crews working on the lines. Keeping anything running in an outage needs proper built-in storage.

Why a kit switches off in an outage

SB 868 covers only systems with a certified feature that stops them sending power into the grid during an outage.^[source] This is often called anti-islanding: it means a kit never sends power onto lines that crews are working on.^[source]

What a kit can't do in a PSPS shutoff

In a Public Safety Power Shutoff, a utility temporarily turns off power to an area to reduce the risk of its equipment starting a fire.^[source] A plug-in kit switches off with the grid. pv magazine's guide for California homeowners also notes that even a 1,200 W AC kit can't cover an evening peak or run a refrigerator through a shutoff.^[source]

What a battery can add

• Some resilience. Bright Saver's white paper argues that plug-in solar paired with a battery can help households through outages, including people who rely on powered medical equipment or refrigerated medicine.^[source] Bright Saver sells plug-in kits.
• Power after sunset. A battery can store midday power for use after sunset.^[source] It adds cost, so compare the battery's price with what it would save you.

Backup-power claims to question

The guide lists "backup power" claims for kits without proper built-in storage and certification as a red flag.^[source] Before you buy a kit with a battery, ask the seller:

1. Does the battery keep powering its own outlets when the grid is down?
2. What can it run, and for how long?
3. Is the complete system, battery included, certified, and by which testing lab?

If you need power for medical equipment, don't rely on a plug-in kit alone. Before you buy any kit, see our checklist and red flags.