In this article, the temperature coefficients of the bifacial passivated emitter and rear cell (PERC) solar module and the full-area aluminum back surface field (Al-BSF) solar module were calculated based on the theoretical model under different module temperatures and irradiances. Meanwhile, the measured temperature coefficients were obtained by testing the performance of bifacial PERC solar module and conventional Al-BSF solar module under different module temperatures and irradiances. The results show that the laboratory measurements are close to the calculated values, and the normalized temperature coefficients of output power for the bifacial PERC solar module are lower than that of the conventional Al-BSF solar module under the same operating conditions. An interesting finding is that the normalized temperature coefficients of short-circuit current for the bifacial PERC solar module are larger than that of the conventional Al-BSF solar module under the same irradiance. This is attributed to lower back surface recombination velocity and higher carrier collection efficiency of PERC solar cells compared with conventional Al-BSF solar cells. Additionally, the operating temperatures of the bifacial PERC solar module and conventional Al-BSF solar module were surveyed outdoor. It is found that the operating temperature of the bifacial PERC solar module is higher than that of the conventional Al-BSF solar module in some cases. However, this tendency is reversed in other cases when these two solar modules work under the same environmental conditions. The conclusion was explained reasonably according to the actual operating conditions of solar modules. The obtained results in this work can provide useful insight into evaluating the field performance of the bifacial PERC solar module.

The regular performance deterioration of P-type crystalline silicon solar modules and module strings caused by potential-induced degradation in a photovoltaic power plant was found in the field. The PID-affected solar modules dismounted from the photovoltaic power plant were further investigated systematically in the laboratory. For the first time, we found that the neutral point of voltage in a module string moved forward to the positive pole for a PID-affected module string as time goes on. Even if low positive voltage is applied to a PID-prone module, it could cause PID. The thermographic and electroluminescence (EL) images of a PID-affected module string also exhibit a regular degradation pattern. This is in good agreement with the measured power loss of the dismounted solar modules under standard test conditions. The results obtained in this paper show that the maximum power degradation rate of solar modules was as high as 53.26% after only one year of operation because of PID in the field. Due to the vast amount of solar modules and incomplete recovery, this is a terrible catastrophe for the owner of a power plant and module producer.

At present, the improvement in performance and the reduction of cost for crystalline silicon solar cells are a key for photovoltaic industry. Passivated emitter and rear cells are the most promising technology for next-generation commercial solar cells. The efficiency gains of passivated emitter and rear cells obtained on monocrystalline silicon wafer and multicrystalline silicon wafer are different. People are puzzled as to how to develop next-generation industrial cells. In this paper, both monocrystalline and multicrystalline silicon solar cells for commercial applications with passivated emitter and rear cells structure were fabricated by using cost-effective process. It was found that passivated emitter and rear cells are more effective for monocrystalline silicon solar cells than for multicrystalline silicon solar cells. This study gives some hints about the industrial-scale mass production of passivated emitter and rear cells process.