Isolated microgrids are promoted as solutions for rural electrification in the Global South but they often encounter difficulties during their lifespan. Despite this, long-term research on microgrid viability and sustain- ability is scarce. Building on existing works, we develop a multidimensional approach to sustainability based on four dimensions: technical, financial, institutional and socio-cultural. This framework is applied to an isolated microgrid in a Senegalese village over a seven-year timeframe, looking at both local and external factors. The unusually long-term approach uncovers the deep roots of entangled and evolving sustainability issues. Our re- sults are three-fold. First, intertwined sustainability factors intensify challenges. Technical challenges exacerbate financial and institutional ones, while the design of the microgrid impacts socio-cultural aspects. This leads to a vicious cycle between the four sustainability dimensions. Secondly, sustainability is mostly affected in the in- terval between technical breakdown and repairs as maintenance delays have repercussions on users' practices and their trust in the MG, as well as the operator's business models. Lastly, MGs are never a completely local system, even if they are designed to be (partially) autonomous. The study thus makes recommendations for researchers, practitioners and decision-makers. A long-term vision is necessary from the MG design stage. External support and funding are essential to ensure the sustainability of microgrids in poor and remote settings, moving away from the image of microgrids as autonomous systems. Future research agendas would benefit from additional case studies with a longitudinal and multiple-scale approach.