Detection of Solar Cell Cracks by Laser Line Induced Lateral Currents and Luminescence Imaging

Electroluminescence imaging is a very powerful technique for PV fault diagnosis, although having to contact electrically the panels during measurement is a complex and time demanding limitation that currently presents a challenge for wide scale field inspections. A light induced luminescence method has the potential to overcome the contacting issue, generating contactless luminescence based PV images. With this technique, a concentrated light beam that will induce lateral currents generates the luminescence signal. The spatially resolved luminescence appears differently in regions of the solar cell with high resistivity, such as electrically isolated cracks. In this paper, we evaluate how the different aspects of the light induced lateral currents are shown in cracks with different severity levels, compared with a non-electrically isolated area, and a control cell in the same PV module. Moreover, the influence of laser intensity and scanning orientation are evaluated.