Defects in photovoltaic (PV) modules severely affect their lifespan and the levelized cost of energy (LCOE). Traditional nondestructive testing (NDT) methods rely on electrical or thermal signatures and are not sensitive to early-stage defects, such as interlayer delamination. This study investigates the use of microwave NDT for detecting delamination in glass-glass PV modules. An electromagnetic model is constructed, and Ka-band (26.5-40 GHz) simulations and measurements are performed using an open-ended rectangular waveguide (OERW) probe. The simulated and measured reflection coefficient results show consistent magnitude and phase shifts in the presence of delamination, validating the model and demonstrating detectability using microwave reflectometry. Furthermore, raster-scanned imaging is applied to both simulated and fabricated samples, revealing defective localization at a standoff distance of 5 mm. The method successfully detects artificial delamination with areas on the order of a few hundred square millimeters in both simulation and measurement. These results confirm the feasibility of microwave imaging for early, non-contact PV module inspection and indicate strong potential for practical large-area deployment.

Nondestructive testing; microwave; photovoltaic modules