Contact Resistance Limitations in Conductive Adhesive and Solder Paste Modules

The reduction of conductive adhesive (ECA) or low temperature solder paste (LTS) in photovoltaic (PV) modules offers a potential path to lowering material costs and reducing the use of limited materials. However, reducing the amount of ECA or LTS beyond a certain threshold results in increased contact resistance due to the reduced total contact area and this detrimentally affects the fill factor (FF) due to series resistance losses. Additionally, insufficient interconnection material can compromise the mechanical strength of the connections, making them less capable of withstanding subsequent handling or thermal cycling stresses. In this study, we employ both simulation models and experimental measurements on minimodules to examine the effects of reducing ECA and LTS amount on contact resistance and FF in both shingled interconnections. To ensure adequate mechanical stability, we incorporate non-conductive adhesive (NCA), which allows us to explore lower material volumes where increases in contact resistance begin to significantly degrade module performance. Our results demonstrate that the strategy of combining reduced ECA or LTS with NCA can offer substantial cost and material savings without sacrificing performance or reliability. The simulation model developed in this work serves as a valuable tool for determining the minimum required amount of interconnection material based on material properties, providing essential guidelines for further optimizing interconnection materials and costs in PV modu les while maintaining both the efficiency and durability of the modules.