A reliable and aesthetically pleasing lightweight (LW) photovoltaic (PV) module for building integration is expected to develop a growing interest in the consumer market. However, its application is still limited by old buildings that are not structurally designed to withstand additional dead weight. We present the results of an inter-laboratory investigation within the solar. NET-ERA project 'Delight'. The present work has countered this challenge through a novel LW module architecture to attain a total weight of <6 kg/m2. This approach replaces glass at the front with a highly transparent polymer foil to maintain optical coupling between the cell and the incident solar radiation. The mechanical rigidity of the LW PV module is provided by a composite sandwich structure (by adhering a honeycomb (HC) core layer between two fiber-reinforced composite skins) at the back of the module. For the skins and the HC, we have investigated two thermoplastic polymers, polypropylene (PP) and polyethylene terephthalate (PET), and present here the first-hand results of a reliability study done on this novel PV architecture. The investigation includes the effects of accelerated environmental aging, hail-impact tests, peel tests, wet-leakage tests, and fire ignition tests at the module level. Furthermore, the degradation due to the stressors, as mentioned above, is explained by performing fundamental characterization at the material's level using techniques like differential scanning calorimetry. Overall, the modules with PP-HC backsheets performed better than that of the PET-HC based candidates.