In the past years, Dutch citizens have experimented with various kinds of innovations to organize the collective production of renewable energy, including shared wind power and solar PV installations. Most of these attempts failed mainly due to legal issues and tax rules. Yet, one model for solar PV on collective roofs was implemented more widely, namely the postcode rose (PCR, postcoderoos): a form of cooperative solar PV production within a set of adjacent postcode areas. Set within a broader transition perspective, this article studies the emergence and evolution of the PCR as an example of a successful social innovation in the energy transition, through an innovation biography and mapping of the evolution of the social and institutional network around the innovation. The various attempts for collective solar PV, with different degrees of success and uptake into the regime, present a key aspect of niche development, namely associational work (circulation and mobilization) focused on regime change. In conclusion, the innovation path of the PCR emphasizes the importance of the political and associational in the energy transition and in transition thinking.