The Berlin Energy and Climate Protection Program 2030 gives solar energy a central role, as it is the most important renewable energy source that can be developed locally. The state government wants to cover 25 percent of Berlin's electricity supply from solar energy as quickly as possible. In the densely populated city, this also requires the roofs of apartment buildings to be used. In the discussion format Wandelwecker on 8 September 2021, Fabian Zuber (Reiner Lemoine Foundation) and Ecologic Institute's Katharina Umpfenbach discussed options transforming the regulation of tenant electricity and local solar power supply. The event was moderated by Valentin Tappeser (IÖW). It became clear that solar expansion can only be achieved at the required speed with a fundamentally new regulatory approach centered around joint self-supply that intelligently links on-site power generation via solar systems with charging of electric vehicles and heat generation.