This paper demonstrates a statistical analysis approach, which uses T-test and F-test for identifying whether the crack has significant impact on the total amount of power generated by the photovoltaic (PV) modules. Electroluminescence (EL) measurements were performed for scanning possible faults in the examined PV modules.
These cracks may lead to disconnection of cell parts and, therefore, to a loss in the total power generated by the PV modules . There are several types of cracks that might occur in PV modules: diagonal cracks, parallel to busbars crack, perpendicular to busbars crack and multiple directions crack.
Only 15.556% of the total PV modules have no cracks. However, 84.444% of the PV modules contains at least one type of the crack: diagonal (26.666%), parallel to busbars (20%), perpendicular to busbars (8.888%) or multiple directions crack (28.888%).
Diagonal cracks and multiple directions cracks always show a significant reduction in the PV output power . Moreover, the PV industry has reacted to the in-line non-destructive cracks by developing new techniques of crack detection such as resonance ultrasonic vibration (RUV) for screening PV cells with pre-existing cracks .
Table 5.4.1 summarizes all effects being detectable with electroluminescence for wafer-based PV modules. The table 5.4.1 also shows the influence of the effects to the electrical parameters of a PV module. Using EL imaging, it is especially possible to detect cell cracks in photovoltaic modules.
Results showed that micro-cracks in PV modules can cause power losses in the range of 30%. The I-V measurement of effected PV modules shows that the power loss due to visible crack depends on crack orientation, inactive area, and the number of cracked cells ( Tsanakas et al., 2016 ).