A Metrological Study of Accurate Indoor Characterisation of Commercial Bifacial Photovoltaic Module With Single Light Source

The IEC TS 60904-1-2 was published to standardize the indoor and outdoor electrical characterization of bifacial photovoltaic (PV) devices. In our previous work, we analyzed the requirements stipulated in the technical specification to limit the unwanted irradiance for single light source characterization, via evaluating two back panel materials of opposite optical properties, and the effectiveness of combining back panel and masking. Expanding on our previous work, we analyzed the impact of back panel optical properties, masking, and distance of back panel from module, on the maximum power of three types of bifacial PV module at three distance under all A configurations described in our previous work. A detailed uncertainty analysis was conducted. By treating the article as intermediate precision condition of measurements, the dominant uncertainty contributions arise from rear-side irradiance, repeatability and thermal stability, and homogeneity. When the back panel is placed between 5 and 10 cm from the module, uncertainty analysis shows that low-reflection back panels with diffusive or specular reflecting surface exhibits comparable results. The PMPP and total uncertainty increase as the distance decreases down to 1 cm. The results signify the importance of back panel at a safe distance of 10 cm behind the module to reduce the uncertainty contribution of rear-side irradiance, thus achieving accurate PMPP measurements. Masking is required depending on the amount of diffuse light present in the laboratory environment. Overall, the distance of back panel from module plays a much more crucial role over the choices of the material and masking.