Weyland is one of hundreds of thousands of people across Germany who have embraced balkonkraftwerk, or balcony solar. Unlike rooftop photovoltaics, the technology doesn’t require users to own their home, and anyone capable of plugging in an appliance can set it up. Most people buy the simple hardware online or at the supermarket for about $550 (500 euros.)

More than 550,000 of them dot cities and towns nationwide, half of which were installed in 2023. During the first half of this year, Germany added 200 megawatts of balcony solar. Regulations limit each system to just 800 watts, enough to power a small fridge or charge a laptop, but the cumulative effect is nudging the country toward its clean energy goals while giving apartment dwellers, who make up more than half of the population, an easy way to save money and address the climate crisis.