Photovoltaic Modules Using a Galinstan Paste Interconnection

Abstract

A shingled silicon photovoltaic (PV) module without busbars on the front side of a solar cell can increase the light-receiving area and provide more power than a conventional PV module. However, there are several issues, such as damage by laser cutting and interconnection by conductive paste. As the number of busbars increases, the laser cutting process increases, and this process damages the solar cell. Additionally, the interconnection process increases as the number of busbars increases. On the other hand, as the number of busbars increases, the finger length can decrease, and the resistance decreases. In this research, a shingled silicon PV module was fabricated by interconnecting of 6 unit cells with various finger and busbar patterns. Photoluminescence, electroluminescence, light current-voltage characteristics and quantum efficiency were used to observe the damage caused by the laser cutting process. Furthermore, we optimized the electrode pattern design for the shingled silicon PV module. The connecting material is very important for electrically connecting the cut unit cell. We used electrical conductive adhesive (ECA) and Galinstan as the interconnection materials. ECA is the most commonly used material for interconnections; in contrast, Galinstan, a liquid metal, is not commonly used as an interconnection material. Therefore, we compared ECA with Galinstan in the shingled silicon PV module. A liquid silicone module method was used to fabricate the module because that method uses a lower pressure and temperature than a conventional silicon PV module process.