Mismatch mechanisms and electrical performance of bifacial and monofacial photovoltaic modules under complex shading

Partial shading reduces power generation and may induce hotspot-related safety risks in photovoltaic (PV) systems. Bifacial photovoltaic (bPV) modules exhibit more complex responses under shading due to their dual-side power generation capability. Previous studies have primarily focused on power-loss phenomena under limited shading conditions, while the underlying mismatch mechanisms remain insufficiently understood. To address this gap, a physically interpretable power calculation model for bPV modules under complex shading conditions was proposed by incorporating the reverse-bias behavior of solar cells. The model was validated using outdoor I–V curves and applied to analyze complex shading scenarios, including the front-side, the rear-side, and the combined front–rear shading. Experimental results demonstrate that the proposed model achieves power simulation errors below 5% and accurately reproduces the “double-step” and “double-peak” mismatch characteristics observed in I–V and P–V curves. Compared with monofacial photovoltaic (mPV) modules, bPV modules exhibit lower mismatch factor (MF) under identical shading conditions. Across different irradiance conditions, bPV modules consistently demonstrate a higher critical average shading ratio for bypass diode activation, thereby delaying the transition of the global maximum power point. This behavior may contribute to a reduced likelihood of hotspot formation under comparable shading conditions. Even under the combined front–rear shading, bPV modules maintain a bifacial gain of 25.6% and a lower MF. These findings reveal the distinctive mismatch mechanisms and superior shading tolerance of bPV modules, providing valuable insights for the design and deployment of PV systems in shading-prone environments.