A study of the annual performance of bifacial photovoltaic modules in the case of vertical facade integration

Despite the apparent benefits of bifacial modules, their application still suffers from a lack of visibility on the performance gain that they can actually provide. In this work, we consider the specific application of vertically oriented bifacial modules, notably for facade integration. We have developed a methodology to evaluate the annual electrical performance of bifacial modules based on three tools. First, a double illumination characterization setup is used in a solar simulator for comparing module architectures. Then, a reduced scale outdoor test bench allows us to evaluate bifacial module performance in a variety of configurations. Finally, a ray-tracing model validated with short-term outdoor data leads to the determination of the annual performance gain. This methodology allowed us to find optimal performance according to the most important parameters of application and module. Specifically, a module architecture using half-cut cells, a parallel cell interconnection, and textured glasses have been analyzed with respect to their influence on the resistive losses which increase in dual side illumination as well as to their influence on the effect of non-uniform and diffuse irradiance on the backside of the module. This work enabled us to give directions for innovative full-size module architectures.