This study advances theory in the politics of sustainability transitions by 1) developing a type of sociotechnical perspective that follows politics into the details of regulatory conflict over system design, 2) analyzing transition politics as a multi-coalition policy field beyond an intra-industry challenger-incumbent relationship, and 3) showing how political conflict includes broader societal change issues. The study also advances empirical research by examining microgrid policy in California and identifying issues that will likely emerge in other parts of the world with growing microgrid deployment. Central issues identified are local and third-party control over front-of-the-meter systems, equity concerns about cost shifting and access by marginalized communities, the tension between broad decarbonization goals and the use of fossil fuels, and the increased importance of local governments and distribution actors in electricity systems. The analytical framework is used to deepen understanding of the causal conditions that affect the outcomes of the conflicts.