The long-term performance stability of perovskite-based photovoltaic (PV) devices under real operating conditions remains in question since these devices are sensitive to moisture, illumination, temperature etc. Two groups of perovskite mini modules with different perovskite active layers in each group have been fabricated and exposed outdoors for the purpose of studying their outdoor performance stability and of identifying differences in their longterm performance that can be attributed to their composition. Preliminary results indicated differences in the long-term stability of the two groups of modules, one group exhibiting less degradation than the other. Furthermore, significant current losses have been detected in all modules under test whilst voltage and Fill Factor losses were found to be lower This assessment also studies long-term trends in defect evolution by comparing spatially resolved electroluminescence (EL) images taken indoors before outdoor exposure and after outdoor testing. Significant changes in EL emission have been detected in the modules before and after outdoor testing due to the increase of degradation pathways in the devices.