Scanning acoustic microscopy analysis of the mechanical properties of polymeric components in photovoltaic modules

Abstract

The characterization of mechanical properties of polymeric backsheet and encapsulation foils of photovoltaic (PV) modules usually involves destructive techniques, such as dynamic mechanical analysis and tensile testing. In this article, we validate the scanning acoustic microscopy (SAM) as a nondestructive characterization method to estimate the mechanical properties of polymeric multi‐layers in PV modules. The acoustic speed inside each individual material is measured and its mechanical properties calculated. For this validation, other techniques are employed to determine the values of density, thickness, and elastic modulus of the foils. The viscoelastic properties of the polymeric foils are temperature dependent. The longitudinal modulus measured acoustically at 15 MHz and the Young's modulus from conventional tensile testing were compared at different temperatures. Both techniques show good agreement regarding the change in mechanical properties caused by temperature variation. The disagreement in the absolute values of these parameters is explained by the different frequency magnitudes at which both measurements are performed. This confirms that SAM is a reliable technique to measure changes in the viscoelastic properties of the foils in PV modules nondestructively, and thus to obtain more information about aging‐induced material changes and degradation.

Nanoindentation Reveals Crosslinking Behavior of Solar Encapsulants—The Methodological Advantages over Bulk Methods

“…Currently, there exists an increased interest from the photovoltaic (PV) industry in a fast and non-destructive method for the determination of the mechanical properties of solar encapsulant to ensure the encapsulation quality after lamination and the long-term stability. To implement this idea of a non-destructive approach, some studies have been proposed using ultrasonic detection [ 1 , 2 ], optical transmission [ 3 ] and mechanical indentation [ 4 , 5 , 6 , 7 ].…”

Nondestructive Defect Detection in Battery Pouch Cells: A Comparative Study of Scanning Acoustic Microscopy and X‐Ray Computed Tomography

“…The reflection of the acoustic waves occurs at interfaces of adjacent materials with different values of acoustic impedance, as illustrated in Figure 1 a. [ 26,28,29 ]…”

“…The reflection of the acoustic waves occurs at interfaces of adjacent materials with different values of acoustic impedance, as illustrated in Figure 1a. [26,28,29] The acoustic impedance, Z, is a material-specific parameter and is calculated by the product of the density of the material, ρ, and the speed of sound inside this material, ν. This leads to Equation (1).…”