Analysis of Shingle Interconnections in Solar Modules by Scanning Acoustic Microscopy

Scanning Acoustic Microscopy (SAM) is applied as a non-destructive testing to image the electrically conductive adhesive (ECA) joints used to connect shingled solar cells. The advantage of SAM is the possibility of imaging the internal structure of the material, which enables the visualization of the depth profile. In this work, we demonstrate the suitability of SAM for detecting ECA failures in shingled cells that are embedded within a solar module. Shingled interconnected cells were prepared by intentionally applying ECA strips equally spaced apart between adjacent cells. Single acoustic images from different layers inside shingle modules were obtained, as well as acoustic cross-sections. X-ray imaging was carried out to compare with the images obtained by SAM. Additionally, Electroluminescence imaging was further carried out to compare the electrical performance of the shingled cells with the physical distribution of the ECA joints. The results reveal that SAM is capable of imaging the structure of the ECA inside solar modules, and distinguishing intact ECA from defective adhesive areas. Therefore, SAM can be applied as a complementary technique to the qualitative analysis of ECA joints.