A shade tolerant panel design for thin film photovoltaics

We analyze the problem of partial shading of thin film photovoltaic (TFPV) panels, using full two dimensional circuit simulations. By accounting for the panel structure and typical array configurations, we can accurately account for the effect of various shading configurations at the cell and panel level. We demonstrate the limitation of external bypass diodes in protecting shaded cells from reverse breakdown, and explore the whole range of shading scenarios and their impact on reverse stress experienced by shaded cells. Based on the analysis, we identify the key aspects of shading problem, and formulate design rules for shadow aware geometrical design of panels. Finally, we present a new radial design for a thin film PV panel, which not only improves the cell reliability under partial shading, but also enhances the array output current.