By 2024, over 550,000 Germans had hung solar panels from their balcony railings and plugged them into wall sockets, turning apartments into mini power plants; within a year, installations surged to 1 million as the simple, roughly €500 technology spread among renters

A solar panel usually means a roof, an installer and a homeowner willing to make a long-term investment. Germany found a simpler way. For apartment renters who do not control a roof, the answer was to put the panels on the balcony instead.

Known as Balkonkraftwerk, or balcony solar, these small systems are designed to be simple enough for ordinary households to install themselves. One or two solar panels can be mounted on a balcony railing, connected to a microinverter and plugged directly into a standard wall outlet.