Growing attention is being paid to imaginaries of energy futures that originate from actors at subnational levels who engage directly with energy transitions, and how these imaginaries compare with national imaginaries. We focus on collectives (e.g., cooperatives, energy utilities or public administrations) that engage with solar PV in Switzerland, a technology that is seen as central to the future of the Swiss energy system. To uncover socio- technical imaginaries, we undertook 21 semi-structured interviews, complemented with a media analysis to ascertain the degree of formation and stabilization of these imaginaries. A dominant imaginary exists at the national level, which is institutionally stabilized, manifested in the Swiss Energy Strategy 2050; and two emerging sub-imaginaries were uncovered, termed adaptive and transformative. The adaptive sub-imaginary, which shows early signs of stabilization, is based on adapting current structures of power and business models, and embracing more techno-economic approaches. The transformative sub-imaginary, in an early for- mation stage, encompasses broader societal transformations, towards challenging power structures as well as technological solutions. Engaging with the diversity of subnational imaginaries and their phases preceding institutional stability has clear policy implications, notably in providing insights into how national imaginaries are interpreted and reproduced, and how sub-imaginaries may gain momentum over time.