Ultrasonic Air-Coupled Generation and Detection of Lamb Waves in Solar Cells and Solar Panels

This paper reports the results obtained using air-coupled ultrasound to generate, propagate and detect Lamb waves in solar cells in the frequency range 0.25 kHz – 1.2 MHz. the combination of high frequencies and large frequency band is aimed to achieve a higher resolution, a more complete dispersion curve and a better mode identification compared with previous works. Tests have been performed on monocrystalline solar cells, results show that it is possible to excite, propagate and sense the A0 Lamb mode in the proposed frequency range. Mode identification is performed by comparing the measured dispersion curve for both phase and group velocity with theoretical calculations. Finally, the technique is tested to measure the anisotropy of solar cells and to test full packaged solar panels.