Behaviour of half-cell modules regarding inhomogeneous irradiance on the rear-face

Half-cell modules are claimed to offer advantages over full cell modules due to reduced resistive losses and a better behavior regarding shading. For bifacial modules of this kind, inhomogeneity of the rear side irradiance, due to their environment, is investigated in order to be well representative in a simulation tool, developed at INES, dedicated to bifacial PV. The tool relies on a ray tracing optical model, enabling the calculation of the rear irradiance on each cell, and an electrical model, calculating the resulting IV curve of each cell. Some experiments have been conducted on specific modules to assess the quality of simulation (of both of the models), in normal and shadowed configurations, and its ability to reflect the mismatch of performance within the cells. Present results are promising: good accuracy is obtained on rather cloudy days, but for clear days further improvements and experimental validation are required to better take into account the real rear irradiance received on each cell.