Performance Assessment of Dual Phase Change Material Integration in Building-Integrated Photovoltaics: A Coupled Thermal–Electrical, Economic, and Environmental Assessment

Building-integrated photovoltaics can reduce building electricity demand and emissions, but elevated photovoltaic operating temperatures reduce conversion efficiency. This study develops a seasonally adaptive dual-phase-change-material photovoltaic system using RT21HC and RT35HC with different melting temperatures and layer thicknesses to provide complementary thermal regulation under varying conditions. A coupled one-dimensional thermal–electrical model is developed using an enthalpy-based formulation to describe phase change and thermal interactions within the multilayer photovoltaic structure. The model is evaluated using 8760 hourly meteorological data points for Tehran and directly validated against published experimental data for a dual-phase-change-material photovoltaic configuration. The validation shows good agreement, with mean absolute percentage errors of 2.13% for photovoltaic temperature and 2.31% for electrical power, and root mean square error values of 0.91 °C and 0.072 W, respectively. Annual simulations indicate that the proposed system generates 499.23 MWh of electricity and can theoretically supply 67.12% of the annual electricity demand of the building. The base-case levelized cost of electricity is 0.050 $ kWh−1, while varying photovoltaic and phase-change-material costs from 70% to 130% changes the levelized cost of electricity to 0.045–0.055 and 0.040–0.059 $ kWh−1, respectively. Delaying phase-change-material replacement from 10 to 25 years reduces the levelized cost of electricity from 0.052 to 0.046 $ kWh−1. The operational carbon dioxide assessment indicates 616.6 kg of carbon dioxide avoided per panel annually, 5% above conventional building-integrated photovoltaics, without representing a full life-cycle assessment.