By Todd Woody in Bloomberg Green Daily

As electricity prices soar and rooftop solar subsidies vanish, some US renters and homeowners are surreptitiously installing solar panels on balconies and backyards without their utility’s permission. Legislation recently introduced in nearly two dozen states would legalize “plug-in solar” systems, jumpstarting a nascent market for an affordable renewable energy source.

Also called balcony solar, these systems typically consist of two to four solar panels connected to wall outlets. They typically cost $2,000 or more and generate enough electricity to power a refrigerator, electronics, and lights, potentially reducing utility bills by several hundred dollars a year. Some plug-in solar systems include batteries to store power for use during peak demand, when electricity rates spike, and during storms or heat waves that knock out the grid.

Millions of balcony solar systems have been deployed in countries like Germany, which regulates the technology. But only about 5,000 have been installed in the US, according to advocates, most without utility authorization. That’s because plug-in solar has remained in the shadows due to a lack of safety standards and often costly requirements imposed by utilities, but that’s changing. Utah in 2025 enacted a law allowing plug-in solar without utility approval, and other states are considering similar legislation, including New York and California, the nation’s largest solar market.

“The impact of California passing legislation would be huge and will get manufacturers to come into the market,” said Kevin Chou, cofounder and executive director of Bright Saver, a Bay Area nonprofit that sells do-it-yourself plug-in solar systems and has pushed to legalize the technology.

Under California legislation introduced in January, residents may install plug-in solar systems without utility authorization. But those systems couldn’t generate more than 1.2 kilowatts of electricity and must be certified by a nationally recognized testing lab. Legislation in other states contains similar requirements.

Utah’s Republican-dominated legislature unanimously approved a plug-in solar bill in 2025, and the state’s Republican governor signed it into law. Although pro-renewable energy Democrats hold a supermajority in the California legislature, the bill introduced by state Senator Scott Wiener, who is running to replace US Representative Nancy Pelosi, is likely to face opposition from some landlords, homeowner associations, and utilities, according to Chou.

Utilities have expressed concern about plug-in solar’s impact on grid balancing if systems feed excess electricity into the network without their knowledge. Landlords may worry about solar panels falling off balconies or how they change the look of a building, he said. Homeowners associations, which regulate everything from house colors to landscaping, may object to the aesthetics of backyard solar.

California’s three big investor-owned utilities currently require plug-in solar owners to apply and secure approval to interconnect to the grid, just as owners of rooftop solar must do.

Chou estimates that more than a thousand plug-in solar systems have been installed in California. But PG&E and San Diego Gas & Electric have not yet received any interconnection applications for the equipment, according to spokespeople.

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