"That’s because most panels are designed to supply power to the grid -- not directly to houses. During the heat of the day, solar systems can crank out more juice than a home can handle. 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. The only way for most solar panels to work during a blackout is pairing them with batteries. That market is just starting to take off. Sunrun Inc., the largest U.S. rooftop solar company, said hundreds of its customers are making it through the blackouts with batteries."
Are batteries a required component for most solar energy system sales? One would hope so - or at least the consumer should be informed of a system's severe limitations. Seems a shame for people to be forced to learn the hard way that they're "renewable energy" system works only as long as the local utility company keeps the power on.