Electrical and thermal performance of double-pass bifacial photovoltaic thermal system in tropical climate

Photovoltaic-thermal (PVT) systems integrate solar electricity and heat production, improving overall energy utilisation by recovering thermal energy that would otherwise be dissipated in standalone photovoltaic (PV) modules, which typically operate at low electrical efficiencies (10–20%). However, most previous PVT studies have predominantly employed monofacial PV technology, while bifacial PV, which can increase electrical yield by 10–30%, has been far less explored in PVT configurations. Moreover, the limited number of existing bifacial PVT (B-PVT) investigations has largely been restricted to numerical simulations or controlled laboratory testing, leaving a clear lack of evidence on real outdoor performance under tropical climate. To address these gaps, a B-PVT prototype was designed, fabricated, and tested using locally sourced materials in Bandung, Indonesia. A five-subsystem energy balance model (comprising glass, upper-air channel, PV/laminate, lower-air channel, and reflector) was implemented as an iterative 5×5 matrix in MATLAB. Field experiments varied air mass flow rates (0.019–0.093 kg/s) under real irradiance conditions (660–970 W/m 2 ) while recording PV temperature, outlet air temperature, and both electrical and thermal outputs. The prototype achieved average electrical and thermal efficiencies of ∼30% and ∼15%, respectively. Higher flow rates reduced PV temperature by ∼10 °C and increased power output by 50–60 W. The model predicted PV and outlet air temperatures with an error margin of 8% and electrical efficiency with an error margin of 1% across the test range. These findings validated the model's robustness and demonstrated that B-PVT systems with double-pass airflow can reliably harness Indonesia's high insolation for combined heat and power generation, informing the design of PVT installations in tropical climates.