Californians Learning That Solar Panels Don't Work in Blackouts

Rooftop Solar Battery Backup helps Californians keep lights on during PG&E blackouts, combining home energy storage with grid-tied systems for wildfire prevention, outage resilience, and backup power when solar panels cannot supply nighttime demand.

Californians have embraced rooftop solar panels more than anyone in the U.S., but amid California's solar boom many are learning the hard way the systems won’t keep the lights on during blackouts.

That’s because most panels are designed to supply power to the grid -- not directly to houses, though emerging peer-to-peer energy models may change how neighbors share power in coming years. During the heat of the day, solar systems can crank out more juice than a home can handle, a challenge also seen in excess solar risks in Australia today. Conversely, they don’t produce power at all at night. So systems are tied into the grid, and the vast majority aren’t working this week as PG&E Corp. cuts power to much of Northern California to prevent wildfires, even as wildfire smoke can dampen solar output during such events.

The only way for most solar panels to work during a blackout is pairing them with solar batteries that store excess energy. That market is just starting to take off. Sunrun Inc., the largest U.S. rooftop solar company, said some of its customers are making it through the blackouts with batteries, but it’s a tiny group -- countable in the hundreds.

“It’s the perfect combination for getting through these shutdowns,” Sunrun Chairman Ed Fenster said in an interview. He expects battery sales to boom in the wake of the outages, as the state has at times reached a near-100% renewables mark that heightens the need for storage.

And no, trying to run appliances off the power in a Tesla Inc. electric car won’t work, at least without special equipment, and widespread U.S. power-outage risks are a reminder to plan for home backup.

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