Thermal, Electrical, and Economic Assessment of Multilayer Phase Change Material Heat Sinks for Photovoltaic Modules at Different Inclinations: A Numerical Analysis

Abstract

ABSTRACT Passive cooling using phase change materials (PCMs) can reduce photovoltaic (PV) overheating; however, its effectiveness depends on PCM properties, layer arrangement, system inclination, and material cost. This study presents a transient two‐dimensional numerical investigation of nine PV–PCM heat‐sink configurations, including six multilayer arrangements and three single PCM reference cases based on gallium, CaCl 2 ·6H 2 O, and RT35HC. Five inclination angles, β = 0°, 30°, 45°, 75°, and 90°, are examined during a 7 h heating period under a constant equivalent heat flux of 1000 W m −2 . Simulations are performed using the enthalpy–porosity method and validated against independent experimental and numerical data. The results show that PCM selection and inclination have a greater influence on system performance than multilayer ordering. Pure gallium provides the most stable thermal regulation and the highest 7 h average electrical efficiency at all inclinations, with values ranging from 11.89% to 11.96%. Among the multilayer configurations, the best performance is obtained by Case 2 at 0° with an efficiency of 8.05%, Case 3 at 30° with 10.09%, Case 1 at 45° and 75° with 10.46% and 10.50%, respectively, and Case 6 at 90° with 10.37%. RT35HC exhibits the strongest inclination dependence, with its average electrical efficiency increasing from 0.29% at 0° and 1.10% at 30° to 11.34% at 75° and 11.33% at 90° because of enhanced buoyancy‐driven heat redistribution. The enthalpy and liquid fraction results further show that stronger natural convection does not uniformly accelerate melting, as it can create both rapidly melted regions and locally trapped solid PCM. The economic analysis indicates that gallium‐containing configurations become progressively less attractive as the gallium‐to‐RT35HC price ratio increases, whereas RT35HC provides the highest cost–performance at steep inclinations. These findings demonstrate that optimal PV–PCM design requires simultaneous consideration of thermal transport, phase‐change utilization, inclination, PCM inventory, and price uncertainty.