This paper describes the outcomes of an interdisciplinary PhD research project on the sustainability of off-grid Photovoltaic Energy Service (PVES) delivery in rural Indonesian communities without access to an electricity grid. It combined social and engineering perspectives to address sustainability issues. The I3A (Implementation, Accessibility, Availability, Acceptability) Sustainable PVES Delivery framework [1,2] was developed in this project as a holistic integration of three main theories: Sustainable Development (SD) [3], Social Capital (SC) [4, 5, 6], and Diffusion of Inovation (DOI) [7], with the WEC (World Energy Council)’s three energy goals (3A) [8] and used to assess the sustainability of three off-grid PVES case studies from Lampung, West Java and Nusa Tenggara Timur (NTT) provinces respectively. The project methodologies included literature research, qualitative field research where PVES had been installed and interviews with a wide range of PVES stakeholders. A key conclusion was that, to be sustainable and equitable, off-grid PVES projects should be implemented in an institutional framework that provided sound project management and addressed PVES accessibility (financial, institutional and technological), availability (technical quality and continuity) and acceptability (social and ecological). Drawing on those insights, ways to enhance off-grid PVES delivery in rural situations in Indonesia were recommended. The outcomes of this PhD research project have since been used as the basis for a successful Australian Development Research Award (ADRA) grant application involving collaboration between UNSW and Indonesian institutions. A companion paper discusses the structure and objectives of the ADRA project and early outcomes from that project.