Active participation of citizens in the sustainable energy transition—particularly in energy communities—is explicitly desired by the European Union and considered vital for a successful transformation of Europe’s energy system. Currently, energy communities, i.e., citizen-led groups generating energy from renewable sources can be found across Europe, though current numbers are small. However, it is expected that the majority of EU households will be active in some form in the generation of energy by 2050. In order to understand how such a development could come about, and if desired, how it could be ensured, we developed and applied a quasi-dynamic model using the Cross-Impact Balance (CIB) approach and with it analyzed and assessed such a transition in detail. Data for the CIB model was derived from case studies, interviews, three surveys including two discrete choice experiments, expert workshops, and complementary secondary data. A central consideration of the model is a differentiated representation of the heterogeneity of actors in society and their interactions. Main results obtained from the application of the model are possible transformation pathways of citizen participation in the energy transition of Germany. A key finding was that if current trends continue, a citizen-driven energy transition based on energy communities will unlikely be successful. We conclude that several framework conditions must change simultaneously from the status quo so that different social groups in society can be active in the generation of energy. These include changes such as the abolition of hindering regulations and the expansion of financial support schemes with a focus on lower socioeconomic groups. Furthermore, only in a combination of conducive social factors such as neighborhood cohesion and conducive social influence, as well as favorable economic conditions, can energy communities become an important player in Germany’s future energy system.