Electrical Characteristics Analysis of Bonded Cells for Shingled Modules

A shingled module fabricated using electrically conductive adhesive (ECA) can increase the light-receiving area and provide greater power than a conventional module fabricated using solder-coated copper ribbons. However, several issues such as damage from laser cutting and poor contact by the conductive paste may arise. In this study, a 15.675 × 3.1 cm² c-Si cut cell was fabricated using a nanosecond green laser, and cell bonding was performed using ECA to fabricate shingled modules. If the laser process was performed with high speed and low power, there was insufficient depth for cut cell fabrication. This was because the laser only had a thermal effect on the surface. The cell was processed to a depth of approximately 46 μm by the laser, and it could be seen that the laser cutting proceeded smoothly when the laser process affected more than 25% of the wafer thickness. The cut cell was bonded by ECA, and the process conditions were changed. The highest efficiency of 20.27% was obtained for a cell bonded under the conditions of a curing time of 60 s and curing temperature of 150°C. As a result, the efficiency of the bonded cell was increased by approximately 2.67% compared to the efficiency of the conventional cut cell. This was because the shadow loss due to the busbar was reduced, increasing the active area of the module by eliminating the busbar from the illuminated area.