Light Soaking Effects on Full-Area and Half-Cut Silicon Heterojunction Solar Cells

Lightsoaking (LS) of n-type silicon heterojunction (SHJ) solar cells is a topic that raised increasing attention of the PV industry. The treatment of n-type SHJ with high light intensity and high temperature in parallel leads to a boost in efficiency () that is driven by improved passivation at open-circuit and MPP (Voc, pFF) and reduced series resistance (RS), both together leading to a higher FF of the cell. Within this paper we investigate the effects of LS and show that LS can be an effective means to modify and improve layer and interface properties. However, to fully take advantage and maximize  the post processing by LS and the individual cell / module processing steps must be well aligned. Here we show that transparent conductive oxide (TCO) deposition conditions can have a significant influence for a given LS treatment. Furthermore, we combine the LS treatment with cell separation and edge passivation technology, the so-called post processing of the cell to overcome losses resulting from separation of half-cut (HC) SHJ cells. Further, we demonstrate that SHJ cells were successfully separated with low loss applying a slim post processing sequence. From these cells a monofacial and a bifacial module were built and characterized. Finally, the topic reliability of the LS gains is shortly addressed.