Forget Rooftops — Bay Area Residents Are Plugging Solar Into the Wall

On a sunny, early summer morning, Matthew Milner waited in his driveway in the Berkeley hills. It was his solar install day, and he was excited. He greeted the installers and walked them around to the back of his house. But instead of pointing to his roof, he pointed to his wooden backyard fence. That is where these solar panels would go, tilted, with their bottom edge on the ground, and top leaning against the fence’s wooden planks.

The installation wrapped up in two hours, demanded minimal paperwork, and damaged Milner’s wallet only marginally, as far as solar installations go. By noon, he plugged in an electrical cord that snaked from the panels into an outlet on the outside of his house. Immediately, solar power coursed toward his electrical panel and then flowed back through his home.

With that, he was offsetting his home’s energy use.

Milner is one of the solar-curious, who are testing the waters by purchasing a small, portable, plug-in display.

“We’d wanted to get rooftop solar, but it’s so expensive,” said Milner, a scientist. The price of rooftop solar in California ranges widely and can cost tens of thousands of dollars. “This allows us to dip our toe in a little bit without having a huge financial cost and see how it works for us.”

Plug-in solar, also called balcony solar, is a new take on an old technology. For years, panels that turn sunshine into electricity have been bolted onto rooftops and largely limited to people who own homes, have well-maintained roofs in prime positions, and a decent amount of cash or good credit.

But plug-and-play solar can hang from an apartment balcony, out a window, or be tented in the backyard — the smaller, more affordable displays offer an attractive alternative for renters and people with no roof at all. They may even appeal to Californians who would have bought rooftop solar but are hesitant after state regulators reduced how much someone can earn by selling excess power back to the grid.

For a long time, the economics of rooftop solar penciled out, said Bernadette del Chiaro, senior vice president for California at Environmental Working Group, who headed California’s trade association for rooftop solar for years. “I think it’s very different now for a consumer.”

On top of this, Congress’s recent budget bill reduced or eliminated solar tax credits.

Now, del Chiaro said, consumers are more likely to say: “‘I’m just going to install my own system, hang it on my own balcony and PG&E never needs to know.’”

Californians, struggling with soaring electricity bills, are eager to adopt the technology.

Advocates believe the state’s market has massive potential. They’re motivated by two examples: Utah, which recently passed legislation allowing the technology to take off once additional safety measures are implemented, and Germany, where millions of solar panels dot balconies across the country.

But there are clear hurdles, and fuzzy ones too. State regulators and utility PG&E said its customers must register the technology before they plug it in. But small solar advocates argue the registration process should be faster for these systems than it is for rooftop solar. It’s time-consuming, costly, and exactly the type of bureaucracy they’re trying to cut out.

A nonprofit called Bright Saver installed Milner’s system — it’s one of the many start-ups championing the small arrays. The organization is hoping to create a movement and plays an umbrella role for companies, policymakers and safety certification organizations.

Bright Saver’s first product is two solar panels and accessories, which can power about a fifth of the average Californian’s energy needs: covering lights and small electronics, maybe even an efficient refrigerator. It can produce 800 watts and costs $2100, but the founders think the costs will drop in the coming years.

The organization estimates it will take Milner, who purchased his system at a discounted rate of $1700, four to five years to make back the upfront investment in the panels through bill savings. That’s about three times faster than how long it takes to recoup the investment from rooftop solar.

Milner was motivated to try out solar because, as a father of two young kids, he wants to take action on climate change. And like most Californians, his energy bills are high, about $75 to $80 per month.

“It fixes our energy cost a little bit, because rates keep rising,” Milner said.

As easy as buying an IKEA-style table

Pranav Myana, 21-year-old founder of Zoltux, an energy company based in San Francisco, is working on his own version of this technology: a shippable set of two lightweight panels, just millimeters thick, together about the size of a medium dining room table top. Myana said you can assemble it in five minutes.

He calls it an “instant solar pod” and is pricing it at $1199, which he estimates will pay for itself in three to four years. The company is taking pre-orders now and plans to ship the product in early fall.

Myana was inspired to build Zoltux after visiting his family’s homeland in India, a town called Sircilla, where the main industry is weaving with electric looms. When power became expensive and inconsistent, mounting debts led to many suicides that, Myana said, included some of his family members.

“It showed me just how fundamental energy was to everything we do,” he said.

Some companies like Bright Saver employ staff to install their panels, but a goal is to cut out professionals altogether. That’s because roughly half the price of getting solar is in labor and “soft costs” like permitting.

The dream is for plug-in solar to be purchased off the shelf and set up by the customer, IKEA-style.

Already, plug-in solar companies are working to add a small battery to their setups to gather extra power, store it and deploy it when the sun goes down.

But plug-in solar has risks, like most appliances. Without safety measures or proper equipment, wires could overheat and ignite a fire, or the systems could send power back to the grid when there’s a power outage, endangering a line worker sent out to make repairs.

Start-ups address these by plugging into a dedicated circuit, using a “smart plug” that can shut the solar panels off if there’s excessive current on the system, or a sensor to shut it off when the larger grid goes down.

Why isn’t plug-in solar already everywhere?

For one thing, there’s no safety standard for a complete plug-in solar system. Safety standards are typically shown by a “UL” stamp, or similar marking, on the back of products, indicating they’ve met requirements set by Underwriters Laboratories, an independent testing organization.

These exist for individual parts of the system only, which some companies assemble and view as sufficiently safe. UL said they are working on a safety standard for a full system.

Plug-in solar does not fit easily into layers of national, state, and local electric code and operates in a regulatory gray area in California, where utilities want customers to register the product as they would a rooftop system.

“There’s these big gaps where it’s certainly not that you can’t do this, but it’s also not clear that you can absolutely do this,” without registering the system, said Kevin Chou, a co-founder of Bright Saver.

To stay within California rules and skirt filling out an interconnection agreement with utilities, Bright Saver’s technology prevents excess power from feeding back into the grid.

PG&E representatives said registration costs roughly $100 to $800 and shouldn’t take much time at all: just an hour if you have all your documents ready to go, with a standard approval time of three days.

Spokesperson Paul Doherty said the utility “supports new technology to make interconnecting [distributed energy resources like plug-in solar] to the utility grid as easy as possible,” but added that “it is essential” for customers to apply for an interconnection agreement, citing safety and reliability.

The California Public Utility Commission also requires an interconnection agreement to connect to the state’s grid, even for systems with UL-certified components, like an inverter. “UL certification ensures the inverter meets safety standards, but it does not eliminate the need for interconnection review and approval,” the agency said in statement.

“They tell you you should, but they do not provide a practical means for it,” said Rupert Mayer, another Bright Saver co-founder. In Germany, customers register their name, address, system size and meter number, he added. It allows a utility to plan its electric load for a neighborhood.

“That is legitimate for the power company to want to know. But if you require someone who plugs in a single solar panel to go through the whole very bureaucratic interconnection process that they would need to go with rooftop solar,” Mayer said, as is the current case in California, “you basically make it prohibitive and put up an unnecessary hurdle.”

As his organization has grown more aware of PG&E’s interpretation of state rules, Mayer said Bright Saver has paused installations like Milner’s, at least in California, and is focused on education instead.

A breakthrough in Utah, inspired by Germany

One way to cut through the gray areas surrounding rooftop solar is to allow it, very clearly, in writing.

That’s what Utah state Rep. Raymond Ward did.

Ward wrote legislation to allow balcony solar after reading an article about its ubiquity abroad.

“I’m interested in anything that helps move towards more abundant energy,” said Ward, a Republican. “Anything that moves towards more clean power, with how that relates to the climate, is important to me.”

He championed legislation allowing people to plug in small solar arrays without a permit or utility fee, so long as they comply with the national electric code and third-party product safety standards. Products with certified components are already on the market.

The bill passed Utah’s state legislature with unanimous, bipartisan support in March. It was quickly signed into law by Republican Gov. Spencer Cox.

“It has turned out to be pretty important, right? A lot of people were watching,” Ward said.

Christian Ofenheusle is one of the architects of Germany’s plug-in solar movement. When he started in 2017, he estimated there were around 40,000 plug-in solar installations. He struggled with many of the problems facing plug-in solar in the U.S. now.

But movement leaders have made the process of getting plug-in solar straightforward through concerted effort. The product is even on sale at IKEA. Now, there are one million documented, and several million more running without formally registering with the government, Ofenheusle said.

Collectively, those panels generate the same amount of electricity as a small power plant that did not have to be built.

But even if there is widespread adoption of this technology, in terms of overall power needs, “balcony solar is a small, small piece” of overall demand, cautioned Dan Kammen, an energy professor at UC Berkeley.

Still, Kammen said plug-in solar matters, in part because “every bit helps.” And also, because panels hanging off your balcony are a talking point.

“A lot of what we do is not just signaling to others, but it’s signaling to ourselves,” he said. And it’s a way to take tangible action.

“The more you learn about solar panels for your home purchases, the more that you can translate that into the business world. And that education is invaluable,” Kammen said.