On the impact of defects in solar modules and the interaction between monolithically interconnected cells

Local defects (shunts) in Cu(In,Ga)Se₂ solar cells and modules reduce the overall performance of the devices. This contribution uses a combination of electroluminescence and lock-in thermography imaging to investigate the effect of shunts on the devices. The experimental results show that shunted cells significantly affect the adjacent cells, i.e. the so-called cross-talk effect. Further analysis of the cross-talk effect with a 2D network simulation shows that the impact of a defect in one cell partly depends on the sheet resistances of the electrodes in the neighboring cells. It is well known that in the presence of spatial inhomogeneities an optimum exists for the electrode sheet resistance. However, we demonstrate that in a monolithically interconnected module one needs to consider both the sheet resistances of the front and back electrodes, as well as the width of the solar cell stripes.