This article shows how long-term development programs struggle to institutionalize renewable energy solutions in the Global South. Our contribution is twofold: (1) Conceptually, we propose and apply a framework to investigate under what conditions and with what effects development partners institutionalize their renewable energy interventions. For the conditions, we build on institutionalization literature and particularly on the Earth System Governance research lens on architecture and agency. For the outcome, we distinguish between rhetorical, policy-related, organizational and practical changes. (2) Empirically, we mobilize this framework to analyze three long-term renewable energy programs initiated by development partners in Indonesia through a qualitative approach. Although these programs trigger rhetorical and partly policy-oriented changes, they struggle to foster new organizational structures or mainstream new political practices. We conclude that scholars must engage more seriously with agency and architecture as critical conditions for externally driven efforts to promote renewable energy solutions in the Global South. © 2025 The Authors