Controlled Introduction of Cracks into Crystalline Silicon Solar Cells and Subsequent Acoustic Excitation

AbstractDue to the high cost pressure in solar module manufacturing over the last years the need for investigation of module quality (reliability, lifetime, security) has become more important. To investigate the long time behavior of solar modules both in the field or in the labit can be beneficial to simulate typical defects in components of solar modules. In this work two different methods are presented to introduce artificial mechanical defects into standard silicon solar cells. Furthermore the dynamic behavior of cracks is investigated during strong acoustic excitation using a self-made excitation setup and photoluminescence techniques.In the first method a steel ball is dropped in a controlled way on a mounted solar cell leading to a reliable introduction of a cross-shaped crack. In the second method a pendulum is used to introduce mechanical edge defects in solar cells which always leads to chipping of silicon but not necessary to crack introduction. By investigation of over 100 samples it can be shown that mc-cells have a higher probability of breaking if initial mechanical defects are present at the edge compared to Cz-cells. Furthermore no evidence was found that the edge isolation method (chemical or laser) could influence the breaking of solar cells with damaged edges. Also it is shown that cracks close to the edge lead to a higher chance of breakage compared to cracks in the center of the solar cell