The sun was shining brightly one August morning in Möckernkiez, a minimalist housing complex beside the leafy Gleisdreieck Park in central Berlin.

Inaugurated in 2018, the innovative, cooperative-run estate is a model of green living. More than 3,000 residents across 471 apartments in the car-free district receive heat and electricity via clean energy such as biogas and rooftop solar.

And two years ago, the residents received a novel boost to their green energy supply when 70 solar panels were installed on their balconies. Today, the panels are dotted all across building façades, hanging beside plants and racks of drying clothes.

“It was the wish of several residents,” says Bernhard Drechsel, technical director at Möckernkiez. “They came together and proposed this. They wanted to make an extra individual effort.”

In doing so, the residents joined the ranks of what are today more than a million people across Germany who have installed balkonkraftwerk (balcony solar), an increasingly popular renewable energy technology that is democratizing access to solar across Europe’s largest economy. While each unit currently only produces a modest amount of energy, the cumulative impact of their large-scale adoption is contributing to Germany’s target of sourcing 80 percent of its electricity from renewable sources by 2030.

Balcony solar — also known as “plug-in” solar, since it can be connected directly to a wall outlet — is accessible to practically anyone that has minimal outdoor space with decent sunlight, including those who may not even have a balcony.

Installation, which requires little more than plugging in the appliance, is easily done without an electrician. And thanks to falling production costs and government subsidies for balcony solar units, which can be bought online or in stores for just a few hundred euros, it’s easier than ever for individuals to produce their own green energy. 

The result is that these panels are opening the solar market to huge numbers of German citizens, including renters previously excluded from access to domestic solar generation due to red tape for rooftop panels, which often requires users to own their residence and to obtain permission from a local utility. 

“Plug-in solar devices help reduce household energy costs and create greater energy independence for citizens, regardless of subsidies or large investments,” says Carsten Körnig, managing director of the German Solar Association (BSW), which represents more than 1,000 solar companies across the country. “They also increase acceptance of climate protection measures and the urgently needed global energy transition.”

Balcony solar emerged in Germany around the 2000s but didn’t catch on until a few years ago, according to Körnig, when policy changes brought plug-in solar devices “out of their niche” and turned them into a consumer product. In 2019, for example, the government passed its technical regulations for plug-in solar devices, allowing them to use standard electrical plugs and feed into the grid via their in-built inverters.

“That made a big difference in Germany,” says Berit Müller, managing director of the Berlin Brandenburg section of the German Solar Energy Society, the country’s oldest consumer protection association for renewables. “Before, obtaining a permit required a lot of paperwork. Now it’s a lot easier [to obtain permission for] than rooftop solar. Balcony solar has exploded in popularity since then.”

Experts like Müller say that the pandemic lockdown also helped fuel the surge in popularity, as people spent more time at home, allowing them to carry out household upgrades. More recently, escalating energy prices in Europe linked to Russia’s invasion of Ukraine made balcony solar even more economically attractive, he adds.

Last year, further policies were passed, with Germany streamlining its regulatory framework for balcony solar. 

The registration process was “simplified considerably,” recognizing that plug-in solar devices are essentially power-generating household appliances, says Müller. Last fall, it also became mandatory for landlords and homeowners to approve the use of plug-in solar devices for tenants, whereas in the past it was up to their discretion, if they were asked.

As a result, the take-up has been lightspeed. As of late June, 1,009,390 balcony solar systems were registered with the German Federal Network Agency, including more than 220,000 added in the first half of 2025 alone. Given many haven’t been officially registered, Müller says that the real figure is likely to be two or three times higher.

Ramona Timmons, who lives in Berlin’s Prenzlauer Berg neighborhood, bought a two-meter-wide balcony solar unit this summer. “I’d been thinking about it for a few years,” said Timmons, an office manager who lives with her partner. “The more energy we can produce without coal, the better for the planet.”

Rock-bottom prices have sweetened the deal: Timmons bought a 800W unit for just €80 after receiving a €250 subsidy from Berlin city authorities.

“It’s basically no cost,” she adds. “The installation was so easy.”

The practical advantages of plug-in solar devices, which quickly pay for themselves, are convincing more and more people. A YouGov survey commissioned by BSW at the end of 2024 found that around eight percent of the 2,043 respondents said they planned to purchase a plug-in solar device within the next twelve months. A further nine percent said they could imagine purchasing a plug-in solar device at some point in the future.

Körnig of BSW says there is a “very large potential” for uptake of balcony solar across the 30 million residential units in Germany’s two-family or multi-family houses. “The solar boom on Germany’s balconies is likely to continue,” he says.

Yet not everyone is convinced. Dieter Wettig, who has a ground-floor apartment in Möckernkiez, says that even if he did have a balcony he would not install a plug-in unit due to the emissions made during their manufacturing.

“Electricity from balcony power plants is not entirely emission-free, mainly due to manufacturing processes,” he says, expressing a preference for wind or hydropower.

Wettig nevertheless added that, during operation, balcony solar systems are “practically emission-free, quiet, and climate-friendly … its contribution to the decarbonization of energy supply therefore remains significant.”

But given their relatively low capacity and the fact that the market is still in its infancy, even proponents admit that plug-in solar devices are only expected to contribute a low single-digit percentage to solar generation capacity in Germany, despite their popularity and increasing prevalence. Regulations currently limit each system to a maximum 800 watts — enough to power household appliances like refrigerators — though if there is enough space, multiple units can be installed.

Dylan Ryan, a lecturer in mechanical and energy engineering at Edinburgh Napier University in Scotland, adds that while balcony solar is undoubtedly becoming more attractive, geographical and political contexts such as electricity prices, building regulations and weather will dictate their popularity elsewhere.

“Germany is further south than Scotland, so there’s more sun, and electricity is more costly there,” he says. “It’s a much more clear-cut offer. But here it’s not the same.”

Ryan, who has calculated the effectiveness of balcony solar in certain settings, adds that the fast-growing market still has a number of planning, workforce and legal issues to iron out.

“There are legal gray areas — authorities often haven’t distinguished between rooftop and balcony solar,” he says. “And at this stage, there’s a lack of expert advice for the public. More workers need to be trained.”

Some manufacturers don’t meet the required safety levels either, which could lead to fires — even if there’s been little sign of that so far, says Ryan.

But those issues could soon be addressed.

In order to guarantee technical safety and to create legal certainty, the world’s first balcony solar product standard is being developed by BSW and will be published in December, enabling manufacturers and testing laboratories to produce and test plug-in solar devices in accordance with the standard.

Batteries are also being developed to store energy from balcony solar units, allowing energy to be used at a later date, increasing the benefits to users.

And the market continues to scale up, in Germany and abroad. Earlier this year, Utah legislators streamlined regulations for homeowners to buy and install them — and Vermont is set to follow suit. The British government is considering allowing balcony solar to be installed in households across the country as part of its solar power strategy. Meanwhile, sun-kissed Spain is emerging as a “rapidly growing” market.

“The German example can be implemented worldwide,” says Körnig.