This is a sustainability-focused guide to maintaining decentralised solar energy systems in public institutions, especially healthcare facilities, where reliable power is critical for life-saving services. It explains why operations and maintenance (O&M) go beyond annual contracts—encompassing preventive, scheduled, and corrective measures that directly affect system performance, patient safety, and staff confidence. The guide lays out practical standards, step-by-step checklists, and common pitfalls to avoid, while also examining the factors that shape effective O&M strategies—such as geography, supply chains, governance, financing, and human resource capacity. Drawing on lessons from diverse contexts, it offers models for defining ownership, building local capacity, integrating remote

monitoring, and ensuring accountability. Ultimately, the manual positions O&M not just as a technical requirement but as a cornerstone for resilient health systems and sustainable energy access.