Study on Tarnishing Mechanism of Grid Lines on Crystalline Silicon Solar Cells

In this paper, the tarnished grid lines on crystalline silicon solar cells was reproduced and recovered successfully by experiments. Some new phenomena have been discovered: the rate of tarnishing is different, which should be affected by sulfur-containing medium in air and the composition of silver paste used in screen printing. The tarnishing mechanism of grid line was investigated by SEM, EDS. It was found that the sulfide was detected on the tarnished grid lines. The effect of tarnished grid lines on electrical performance and solderability was also analyzed. The results show that with the aggravation of tarnishing, the solderability of solar cells becomes worse, but the electrical performance is not greatly affected.