California Legalizes Plug-In Solar Panels for Homes and Apartments

By Matt Simon for Grist.

As free and abundant as sunlight may be, harnessing its power remains stubbornly difficult for homeowners. While the cost of solar energy has plummeted more than 90 percent in the last decade, panels remain a significant investment. And it’s not as easy as just slapping panels on a roof, as your home may need electrical upgrades too.

It doesn’t have to be this way. Countries like Germany have encouraged the proliferation of balcony solar, also known as plug-in solar: smaller, cheaper arrays that hook into a home’s electrical outlets. This offsets some of a residence’s energy use, saving users hundreds of dollars a year, and opens up solar energy to renters with balconies or backyards. As a bonus, the less power homes have to draw from the grid, the less stress they put on the system, especially during heat waves when everyone is running energy-hungry air conditioners.

On Wednesday, California officially got in on the balcony-solar action as Governor Gavin Newsom signed a bill allowing residents of the nation’s most populous state to adopt the technology. It joins a handful of states, like Utah and Maine, in seeing the potential of the technology to generate clean electricity and save residents money as energy costs rise.

“This technology is very important and very powerful,” state Senator Scott Wiener, who authored the legislation, said during a press conference Thursday. “And what this bill does is eliminate the massive barrier to people using plug-in solar, which is that you’d have to go and negotiate an interconnection agreement with PG&E or the other utility.”

The proliferation of plug-in solar marks a fundamental shift in how the electrical grid operates. Historically, utilities have generated electricity by burning fossil fuels like coal and natural gas. When demand rose, like when people returned home at the end of the day and switched on appliances, they’d just ramp up production. This kept the system in a sort of equilibrium, a constant balance of supply and demand.

That, though, doesn’t quite work the same with renewables like wind and solar. If demand is holding steady and the sun is setting, a utility isn’t generating as much electricity with its panels. Same with wind, if the skies suddenly calm. So in addition to building out wind and solar farms, utilities are deploying huge batteries to save that energy for later use. This creates a more flexible grid that can still hum with electricity when things are dark or calm.

This transformation is turning you, the consumer, into a more active participant in the grid. For years now, homes with solar have sent excess energy back to the grid. While plug-in solar might generate a fraction of what you’d get from a roof covered in panels, it can still help make the grid more flexible. Instead of feeding the system, it reduces the amount of electricity drawn from the grid. Scaled across a whole city, these small reductions can add up, offsetting some of the growth in demand from things like AI data centers and electrification. (Think induction stoves needing electricity instead of natural gas, and EVs charging instead of burning fuel.)

“This is one of the most immediate, concrete, tangible, real, and affordable things that we can do to start to get control of our high energy costs, but also save our planet,” Bernadette Del Chiaro, senior vice president for California at the nonprofit Environmental Working Group, said during the press conference. “So it’s really a twofer.”

Basically, plug-in solar could help reduce congestion in the system at peak times — when it’s hot out and everyone’s running their AC, there’s also plenty of sun to strike the panels. It’s turning homes and apartments into a distributed network of tiny power plants. “It’s really ideal to use renewable electricity exactly where it’s generated,” said Amanda Smith, a senior scientist focusing on the built environment at Project Drawdown, a climate solutions nonprofit.

This increased interactivity in the grid comes as utility bills continue to skyrocket. Basic plug-in solar systems will set you back a few hundred dollars, and you can potentially make back that money with energy savings in around four years. (The higher the energy costs in your state, the quicker you’d get that return on your investment.) Still, for a lot of households, that’s a major investment, so ideally a state also provides rebates for people to adopt the technology.

With California now aboard the plug-in solar train, your state may well follow. “The big reason this is a big deal really is because it’s the most affordable way for people to actually participate with solar PV,” Smith said. “Whatever happens in California is going to influence, I think, a lot of other future state markets. So it’s going to be a key one to watch.”