Multi-Physics Analysis of Phase-Change Material-Adaptive Reflector Photovoltaic–Thermal Systems: A Combined Thermo-Economic and Exergy Perspective Using Computational Fluid Dynamics and Finite Element Analysis

Abstract

Abstract. This study presents a novel thermo-optically coupled photovoltaic–thermal (PVT) system that integrates an actively controlled adaptive reflector with a phase-change material (PCM) thermal buffer, investigated through a fully transient computational fluid dynamics—finite element analysis multi-physics framework. Unlike conventional PVT or reflector-assisted designs, the proposed configuration introduces a thermally responsive feedback mechanism that dynamically adjusts reflector inclination based on real-time photovoltaic (PV) surface temperature, enabling simultaneous optical enhancement and thermal regulation. The numerical results demonstrate that this integrated control strategy effectively constrains the PV operating temperature near the PCM melting point (52 °C), even under peak irradiance and elevated ambient conditions. As a result, the proposed system achieves a combined energy efficiency of 72.5% and a maximum exergy efficiency of 69.1%, representing improvements of 18.3% and 14.7%, respectively, over a conventional non-adaptive PVT baseline. Furthermore, entropy generation is minimized to 0.038 W/K at the optimal reflector angle (65 deg), confirming a substantial reduction in thermodynamic irreversibility. The techno-economic assessment reveals that an optimized PCM mass fraction of 0.22 shortens the payback period to 3.4 years, demonstrating that the exergy gains outweigh the additional material and control costs. Overall, this work establishes a previously unexplored synergy between adaptive optical concentration and latent-heat thermal buffering, providing a scalable and high-exergy design framework for next-generation low-concentration PVT systems in building-integrated and distributed energy applications.