Failure analysis of PV modules using scanning acoustic microscopy

Abstract: Failure analysis and reliability testing of PV modules involve destructive and non-destructive testing (NDT) of single and laminated components. Nevertheless, testing of laminated PV components non-destructively remains a challenging task. The Scanning Acoustic Microscopy (SAM) is an NDT which has the advantage of being sensitive to interfaces, and it provides a direct measurement of acoustic data (time-of-flight, TOF) from the internal interfaces of materials. The present study demonstrates the potential of SAM for the failure analysis of PV modules. The core objectives include (1) main analysis parameters and strategies, as well as (2) the characterization of PV module defects and degradation by SAM, Dark Lock-in Thermography (DLIT), and Electroluminescence (EL) upon artificial aging tests.
For the investigations, PV modules were laminated with polymeric backsheets (BS) and ethylene vinyl acetate-based (EVA) encapsulants, monocrystalline solar cells, and PV glass. The results show that acoustic investigations from the rear side of the modules, i.e., through the BS, at 30 MHz are the most adequate to investigate PV modules. Besides, several acoustic images obtained from specific regions within the module stack enabled locating and imaging defects, such as entrapped air along the busbars, bubbles inside the EVA, and cracks. The sensitivity of SAM to air gaps lies in the extreme acoustic mismatch at an air interface. Moreover, acoustic cross-sections allowed the visualization of how bubbles within the EVA shrank due to aging, and the results were consistent with those from DLIT. The results on the temperature dependence of the acoustic waves revealed that the TOF in the BS and EVA increases sensitively to temperature, especially in the EVA. The findings on the aging tests show that the TOF in the BS and EVA decreases in response to damp heat aging. This behavior corresponds to an increase in the wave velocity in the polymers and might be likely related to an increase in polymer stiffness with aging. In conclusion, this study demonstrates that SAM is advantageous over other NDT methods, for example, in detecting the exact location of defects, visualizing the vertical profile of PV modules, and measuring acoustic properties of polymeric layers in response to material changes. In addition, the findings highlight the potential of SAM for the non-destructive analysis of the elastic properties of the polymeric layers in PV modules

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Universität Freiburg, Masterarbeit, 2019

Classification and Topics

• Keyword: Acoustic microscopy

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2020
• Creator: Mesquita, Laila
• Contributor: Wirth, Harry ; Reindl, Leonhard M. ; Glunz, Stefan ; Pitta-Bauermann, Luciana ; Albert-Ludwigs-Universität Freiburg. Fakultät für Umwelt und Natürliche Ressourcen

Further information

• DOI: 10.6094/UNIFR/166734
• URN: urn:nbn:de:bsz:25-freidok-1667340
• Rights: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:53 PM CET