Background: Sociotechnical transitions require pressure to be exerted from inside or outside of the prevailing 'regime', without which various path dependencies combine to maintain the status quo. Change agents including policy entrepreneurs within the regime, or civil society voices outside, can be sources of such pressure. However, in illiberal democracies or authoritarian regimes, these voices may be little heard or even suppressed. With the premise that this situation calls for protected transition spaces for policy development that are outside of formal institutions, so that policy windows may be taken advantage of should they arise, this paper applies a transdisciplinary transition management arena (TTMA) process (Noboa and Upham, Energy Res Soc Sci 46:114-124, 2018), whereby civil society and other stakeholders can be engaged in the envisioning of new energy futures. Results: With an example of such an arena in Ecuador and presenting a rationale and design that draws on transdisciplinary research and transition management theories, problem statements, visions and strategies for a more decentralised energy system were set out, as generated by participants from government, NGOs, business and academia. The visioning process was evaluated and an analytical framework is proposed, by which to guide energy transition policy analysis in similar contexts in the future. Conclusions: Although compromised in illiberal democracies, sociotechnical transitions benefit from the voices of change agents through the building of new alternative discourses, stimulating policy entrepreneurship and crafting readiness for policy windows. The new alternative energy visions that were produced by participants in the process described here emphasise distributed renewable and sustainable generation, decentralised decision-making at subnational level, participatory energy planning governance and heterogeneous poly-technological solutions at small and medium scales.