P2 laser patterning of the perovskite layer for serial monolithic integration was systematically investigated by laser ablation using nanosecond laser pulses at varied laser fluences. The correlation of the laser impact to the morphology, composition and electrical functionality was analyzed in detail by several surface-analytical techniques. It is found that material removal via stress-assisted ablation is strongly influenced by thermal processes. The formation of PbI 2 containing residuals was evidenced, presumably causing contact resistance losses through the P2 interconnect. From these results loss factors in laser-based serial interconnection of perovskite solar cells were identified, allowing for process optimization for upscaling to industrial module sizes.