Californians Learning That Solar Panels Don’t Work in Blackouts

We are often told that installing solar panels on our homes can be a great way to ensure that the lights stay on in the event of a blackout, but it turns out that this claim is misleading. According to an article in Bloomberg:

“Californians have embraced rooftop solar panels more than anyone in the U.S., but 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. 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 some of its customers are making it through the blackouts with batteries, but it’s a tiny group — countable in the hundreds.

The problem is that battery back-ups are incredibly expensive. A Tesla Powerwall 2 has a capacity of 13.5 kilowatt hours (KWh) and after installation costs between $9,800 and $15,800.

The average Minnesota family uses 748 KWh per month, or about 24 KWh per day. This means it would take two Tesla Powerwalls to provide about 24 hours of electricity for a Minnesota home at a cost of $19,00 to $31,600, and this does not include the cost of the solar panels needed to charge them.

Solar and wind advocates often claim that these sources of electricity will make the grid more resilient, but when the chips are down during a polar vortex or during a blackout, it seems renewables simply can’t deliver.