Optimization analysis of the back surface treatment process for monocrystalline silicon solar cells

To further enhance the photoelectric performance and conversion efficiency of monocrystalline silicon PERC solar cells, it is necessary to optimize the back surface process. This paper studies the polishing, passivation coating, and grooving processes on the back surface of monocrystalline silicon PERC solar cells. Through experimental comparison, alkaline polishing was chosen as the polishing method, resulting in a 4.7% increase in cell efficiency, a 0.35 A increase in short-circuit current, and a significant 19.1 mV increase in open-circuit voltage (Voc). For the coating equipment, N devices with uniform film formation, good passivation effect, low fragmentation rate, and less dust were selected. In terms of the SiNx film thickness process, a thickness of 150 nm was adopted for optimization. The experiment found that as the film thickness increases, the open-circuit voltage (Voc) also increases. However, the change in electrical performance forms a barrier layer between the paste and the silicon substrate, reducing the contact area between the paste and the substrate and increasing the series resistance (Rs). Comparing the back surface grooving experimental data, it was found that the Dot pattern had the best effect at the same aperture width.