Albedo-Dependent Bifacial Gain Losses in Photovoltaic Modules With Rear-Side Support Structures

Bifacial photovoltaic (PV) modules can generate power even from rear-side solar irradiance. Consequently, the rear side of the bifacial PV module must not be hindered by structures. However, structures such as beams are often installed behind modules to ensure structural strength and for various other reasons. In such cases, the output power of the bifacial module is reduced because of partial shading on the rear side. This study entailed an analysis of the albedo dependence of the bifacial gain losses in bifacial modules due to inherent partial shading produced by rear-side support structures (e.g., mounting, frame, and beams). An analysis method combining ray tracing and electrical circuit simulation was implemented and verified through field experiments. The results demonstrate that the bifacial gain decreases nonlinearly at high albedo when the beam is closely attached to the rear side of the module. This loss is reduced by half upon placing the beam at a distance equivalent to the thickness of the beam from the module. The results also indicate the mismatch loss caused by each part of the module's support structure.