Scanning Acoustic Microscopy as a Non-Destructive Method for the Investigation of PV Module Components

The application of new non-destructive testing for the inspection of photovoltaic modules is needed to advance the assessment of module quality and, thereby, improve their long-term performance. Scanning Acoustic Microscopy (SAM) has proved to be a powerful technique for the investigation of failures and defects in a great range of materials, including solar cells and modules. In this work, defects in PV modules are analyzed by SAM and the images are compared with well-established non-destructive methods, such as Dark Lock-In Thermography (DLIT) and Electroluminescence (EL). Acoustic micrographs were collected from different layers of the module and allowed the visualization and assessment of depth profiles of the embedded PV module components individually. SAM can detect irregularities on the encapsulant, backsheet and the solar cell at high lateral resolution and help elucidate defects detected with the other techniques. Moreover, the acoustic beam can be focused at the encapsulant/cell interface to visualize eventual failures occurring on these two layers separately. Therefore, SAM delivers complementary information to EL and DLIT on the quality of PV modules.