Module-Based Supercapacitors: Potential Energy Storage Solutions for Large-Scale Photovoltaic Systems

Intermittency is an inherent characteristic of photovoltaic (PV) power generation and results in high ramp rates of the generated power. This article explores the feasibility of integrating supercapacitors at the PV module level, aiming to reduce the power fluctuations of PV systems and control the power ramp rate into the power grid. First, an equivalent circuit model of a single-phase grid-connected PV system based on module-based supercapacitors is proposed, and a power ramp rate control scheme is established. Then, experimental setups for a single-phase grid-connected PV system based on module-based supercapacitors are implemented, and the computational model is verified through experiments. Finally, using the verified computational model and the proposed control scheme, the module-based supercapacitor sizes for different PV system sizes (PV module, rooftop, small system, large system) that meet specific ramp rate requirements under different ramp rate limits (5, 10, 15% min⁻¹) are compared. Case studies show that large-scale PV systems with geographical smoothing effects help to reduce the size of module-based supercapacitors per normalized power of installed PV, providing the possibility for the application of modular supercapacitors as potential energy storage solutions to improve power ramp rate performance in large-scale PV systems.