A Systematic review of the design and optimization of a Hybrid Solar-PV, battery storage, and diesel generator system for sustainable electrification of Kalangala Island, Uganda

Access to reliable, affordable, and sustainable electricity is fundamental to socio-economic development, particularly in remote and underserved regions. In response to escalating concerns over climate change, energy insecurity, and the limitations of centralized grid systems, hybrid renewable energy systems integrating solar photovoltaic (PV), hydropower, diesel generators, and battery storage have emerged as robust alternatives to conventional energy models. This study presents a systematic review of 44 peer-reviewed articles focused on the design, performance, and optimization of hybrid energy systems in off-grid and weak-grid contexts. The review identifies infrastructure aging, load variability, inadequate storage capacity, and persistent reliance on fossil fuels as key challenges undermining energy reliability, even in grid-connected scenarios. A detailed technical synthesis is conducted, evaluating critical factors influencing hybrid system performance, including solar irradiance variability, PV cell and module efficiency, thermal and angular effects on PV output, and hydropower classification based on head height, capacity range, and operational mode (e.g., run-of-river vs. reservoir-based systems). Solar PV is emphasized for its high resource potential and modular scalability, while hydropower, particularly low-head and run-of-river schemes, is examined as a geographically suitable complement for island settings such as Kalangala District, Uganda. The analysis also highlights the pivotal role of microgrid architectures and energy management systems in enabling real-time optimization, resilience, and cost-effectiveness. Aligning with national and continental development frameworks, including Uganda Vision 2040 and the African Union’s Agenda 2063, the study concludes that a well-optimized solar–hydro–diesel–battery hybrid microgrid, leveraging existing infrastructure and modern control strategies, can serve as a replicable model for the sustainable electrification of remote island communities.