Unravelling Temperature Profile through Bifacial PV Modules via Finite Difference Method: Effects of Heat Internal Generation Due to Spectral Absorption

This study investigates the complex heat transfer dynamics in multilayer bifacial photovoltaic (bPV) solar modules under spectrally resolved solar irradiation. A novel numerical model is developed to incorporate internal heat generation resulting from optical absorption, grounded in the physical equations governing light-matter interactions within the module’s multilayer structure. The model accounts for reflection and transmission at each interface between adjacent layers, as well as absorption within individual layers, using the wavelength-dependent dielectric properties of constituent materials. These properties are used to calculate the spectral reflectance, transmittance, and absorption coefficients, enabling precise quantification of internal heat sources from irradiance incidents on both the front and rear surfaces of the module. The study further examines the influence of irradiance reflection on thermal behavior, evaluates the thermal impact of various supporting materials placed beneath the module, and analyzes the role of albedo in modifying heat distribution. By incorporating spectrally resolved heat generation across each layer often simplified or omitted in conventional models, the proposed approach enhances physical accuracy. The transient heat equation is solved using a one-dimensional finite difference (FD) method to produce detailed temperature profiles under multiple operating scenarios, including Standard Test Conditions (STC), Bifacial Standard Test Conditions (BSTC), Normal Operating Cell Temperature (NOCT), and Bifacial NOCT (BNOCT). The results offer valuable insights into the interplay between optical and thermal phenomena in bifacial systems, informing the design and optimization of more efficient photovoltaic technologies.