Optimized voltage and current matching in a mechanically stacked bifacial III–V/Si tandem solar module via spectral albedo illumination and energy yield simulation

Abstract

Overcoming the efficiency limits of single-junction silicon photovoltaics, this study presents a high-efficiency mechanically stacked III–V/PERC tandem solar module designed for scalability. The architecture integrates a III–V multijunction top cell with a bifacial PERC silicon bottom cell, achieving precise voltage matching through series connection and current matching via rear-side albedo illumination. Under one-sun front and optimized 0.4-sun rear illumination, the tandem device achieved a record efficiency of 36.07%, with a short-circuit current density of 15.16 mA cm⁻² and a fill factor of 83.19%. System-level simulations (PVsyst) for a 500 kW installation validated these experimental results, predicting an annual energy yield of 721 MWh. This significantly outperforms standalone PERC (675 MWh) and III–V (658 MWh) systems, exhibiting a superior specific energy yield of 1442 kWh per kWp per year. By demonstrating improved performance over previous tandem designs through flexible mechanical stacking and bifacial light utilization, these findings establish a commercially viable pathway for deploying high-efficiency tandem modules in real-world, high-albedo applications.