Power Outages: SF, Waymo, generators and batteries

Power outages are an increasing reality for us, as electrical grids face unprecedented strain from extreme weather and aging infrastructure. This vulnerability was starkly illustrated locally on December 20, 2025, when a substation fire plunged nearly one-third of San Francisco into darkness, disrupting holiday transportation and retail for over 130,000 residents and businesses. (And by another outage in Burlingame last week.) Although this outage didn’t affect my own home, I was in SF when this happened - and got stuck at a blacked-out intersection in a Waymo!

Increasing power outages

JD Power highlights the increasing nationwide trend in outages - nearly one-half of americans experienced a power outage in the first half of 2025, with the average length of the longest outage lasting over 12 hours!

My experience in the SF power outage

The December 20 outage in San Francisco backs this data up - in this outage, 1/3 of the city was blacked out for almost 8 hours, with the last group of 3,800 customers out for a straight 63 hours.

That day, the show we were supposed to be seeing was canceled due to the outage, so three of us took a Waymo from the Laurel Heights neighborhood, which had power where we were, to Japantown - which also had power. However, the route we took did not - it was eery driving along entirely dark streets in a driverless car, but the Waymo had no problem navigating at first. Once we hit the first blacked-out traffic light intersection, problems started to show up. The Waymo was confused for a bit, hesitating fitfully - but we made it through. However, when we got to the busy intersection at Divisadero with four lanes of cross-traffic, the Waymo froze. Stuck in the middle of the road, we contacted rider support from the car - the video below shows what happened next, starting about two minutes after we connected with the support rep.

We walked the remaining five blocks to Japantown. On the left side of the street the lights were on, on the right side they were out. Fortunately, the Japan Center had power. Leaving Japantown later, we switched to Uber!

What caused this outage?

It was ironic that the exact same outage, affecting 130,000 customers on December 20, happened 22 years earlier to the day. And another one happened in 1996. NBC reported on this history of trouble at the Mission Street PG&E substation, which provides power to about 1/3 of the city.

Old infrastructure

The PG&E Mission substation was built more than 75 years ago, detailed at the time in a technical document by PG&E. After the fire in 2003, the CA PUC’s report cited a couple key causes:

The root cause of the incident was a cable failure in a switch cabinet. The cable failed explosively, which caused a bus located above it to catch on fire. Over time, vertically installed cable with oil impregnated paper insulation loses its insulating capability because the insulation dries out, resulting in a short circuit....The 1996 Mission Substation fire revealed that the insulation used in the auxiliary buses is flammable and does not self extinguish, but no steps were taken to mitigate this vulnerability.

Another detail highlights how they had to shut down the entire substation (twice) for firefighters to find and fight the fire:

At 5:57 p.m., all transmission breakers at Mission Substation were opened by the San Mateo Control Center (SMCC), effectively de-energizing the substation and terminating power to almost 100,000 PG&E customers, a loss of 150 MW or 22 percent of the load in San Francisco.

Given this detail, it’s pretty clear that PG&E had to again shut down the entire substation for 6-8 hours to fight the fire on the most recent outage, and that’s why so much of the city’s power went out.

Generators on 24th Ave

We don’t yet know the official cause of the most recent fire/outage, but there is a clue: PG&E had to install six massive generator containers on the street on 24th Ave, outside a smaller substation. (Even PG&E has to use emergency generators.)

This most likely means some of the circuits or equipment at the Mission substation supplying the 24th Ave substation were destroyed by the fire. Another clue as to the source is that it appears the outage first started with 40,000 customers in that area - Sunset and Richmond districts, Golden Gate Park, and the Presidio.

What to do about it

While some people are calling for the takeover of the electric infrastructure by the city, what can you do about power outages in the short term? With the increase in weather-related disasters (and the threat of earthquakes in California) updated infrastructure alone may not solve this problem.

There are quite a few options available - I wrote an article for Stormentum, a company that’s looking to reduce the cost of whole-home battery-backed solar systems, outlining backup electricity options. They range from a portable power station, all the way up through whole-home generators or home battery systems.

Batteries are taking over

It used to be that a portable generator was the most common homeowner solution to power outages. But Google Trends data highlights how more and more people are looking to battery-run portable power stations to solve this problem... driven by the relentlessly dropping cost of batteries, and the convenience and low-maintenance of battery backup. Plus, they work inside, making them a good option for apartments.

Of course, batteries run down and generators fail or run out of fuel - but with batteries, low-cost (ie, ~$150 for a 400-watt panel) solar panels can be setup and plugged in to a portable power station to recharge them from the sun for resiliance through longer power outages. Companies are even starting to package batteries and “balcony solar” together in a package:

• In Germany, Ikea sells a do-it-yourself balcony-solar-and-storage kit through a partnership

• Startup Raya Power is pre-selling a packaged solar setup with battery

• Many of the traditional portable power station manufacturers sell bundles with a range of prices and capacities

With power outages increasing and technology failing in uncertain ways (Waymo), having your own plans and backups for when technology and infrastructure fails is the most important thing!