In future urban energy systems, smart grid systems will be crucial for the integration of renewable energy. However, their deployment has moral implications, for example regarding data privacy, user autonomy, or distribution of responsibilities. ‘Energy justice’ is one of the most comprehensive frameworks to address these implications, but remains limited regarding smart grids, and regarding concrete guidelines for designers and policymakers. In this paper, we fill this gap by answering the following research question: How do design choices in smart grid projects impact energy justice? Thereby, four smart grid pilot projects are evaluated in a comparative qualitative case study research design. Data was collected through semi-structured interviews and a content analysis. Our findings contribute to the energy justice literature with insights regarding the design for distributive, recognition, and procedural justice. They underscore the importance of fairness in data governance, participatory design, user control and autonomy, technology inclusiveness, and the design for expansion and replication. Future research should explore the feasibility to govern smart grids as commons and the relationship between trust and perceptions of justice. We conclude with policy recommendations for funding future smart grid experiments and for facilitating the implementation of storage through electricity sector regulation.