A review of solar cells technology integration and energy management in drones for flight endurance

This paper presents a comprehensive and systematic review of solar-powered unmanned aerial vehicles (UAVs), with a particular focus on how solar cell technologies and intelligent energy management systems can be integrated to overcome the fundamental limitation of flight endurance. As conventional battery-powered UAVs are constrained by low specific energy and frequent recharging requirements, solar-assisted architectures offer a promising pathway toward persistent and near-perpetual flight. Following PRISMA guidelines, this review analyzes 60 peer-reviewed journal and conference papers published over the past decade, combining bibliometric mapping and qualitative synthesis to identify dominant research themes, technological trends, and unresolved challenges. The paper systematically examines the complete energy pathway of solar-powered UAVs, encompassing photovoltaic energy harvesting, maximum power point tracking (MPPT), energy storage, battery management systems (BMS), and energy-aware flight control. Key solar cell technologies—including monocrystalline silicon, gallium arsenide (GaAs), thin-film, amorphous silicon, and emerging perovskite cells—are evaluated in terms of efficiency, power-to-weight ratio, flexibility, and suitability for low-altitude long-endurance (LALE) and high-altitude long-endurance (HALE) platforms. The review highlights how incremental gains in photovoltaic efficiency alone yield diminishing returns unless accompanied by aerodynamic optimization, lightweight structural design, and advanced power management. Energy storage is identified as a critical bottleneck for sustained operation, particularly during night-time and low-irradiance conditions. The paper analyzes the role of lithium-ion, lithium-sulfur, and emerging solid-state batteries, emphasizing the importance of sophisticated BMS functions such as state-of-charge and state-of-health estimation, thermal management, and cell balancing. Advances in MPPT algorithms—from classical perturb-and-observe and incremental conductance methods to AI- and machine-learning-based approaches—are reviewed, demonstrating how intelligent MPPT and energy management can significantly improve power extraction under partial shading and rapidly varying environmental conditions. Environmental and operational factors, including altitude, latitude, seasonal irradiance variation, cloud cover, and mission planning strategies, are shown to strongly influence endurance and viability. The review further synthesizes historical and contemporary solar UAV platforms, revealing clear design trade-offs between endurance, payload capacity, structural robustness, and operational flexibility. Finally, future research directions are outlined, highlighting the convergence of high-efficiency and flexible solar cells, AI-driven MPPT and energy management, next-generation battery chemistries, and aerodynamic–structural co-design. Collectively, these developments position solar-powered UAVs as a transformative class of aerial platforms capable of bridging the gap between conventional aircraft and low-altitude satellites for long-duration surveillance, environmental monitoring, and communication applications.