The invention discloses an online defect detection method for a main-grid-free photovoltaic
cell panel, which comprises the following steps of: obtaining a life
distribution diagram of a main-grid-free photovoltaic
cell through time-resolved
photoluminescence, and obtaining a heat dissipation diagram of the main-grid-free photovoltaic
cell through optically-induced phase-locked thermal imaging; an ultrasonic diagram of the main-grid-free photovoltaic cell is obtained through
laser ultrasound; preprocessing and registering the life
distribution diagram, the heat dissipation diagram and the ultrasonic diagram so as to uniformly map the life
distribution diagram, the heat dissipation diagram and the ultrasonic diagram to a cell coordinate
system, extracting minority carrier life, heat dissipation power,
ultrasonic propagation time
delay offset and scattering energy, and forming a multi-
modal feature together with a thermal phase; and based on the abnormal
score, performing defect detection and classification on the multi-
modal features of the possible defect area to obtain classification results of electrical defects, thermal defects and mechanical defects. The invention also discloses a
system for realizing the method. According to the invention, full-coverage detection of electrical, thermal and mechanical defects is realized.