Bubbles formation on the photovoltaic cells fingers: Visual inspection of 30-year-old modules

Understanding photovoltaic modules degradation is one of the keys utilized to develop and design new high-performance materials. This work focuses on analyzing the bubbles formation on the front of the PV module, particularly on the fingers of the PV cells. The paper investigated several PV modules operating in Algeria under two different weather conditions (warm and dry climate, moderate and humid climate) for almost 30 years. A visual inspection was carried out on 60 modules, and the findings obtained in terms of degradation defects were discussed. During the visual inspection, the formation of bubbles was observed only in the encapsulant above the PV cells within the PV module. However, these bubbles position is consistent with other defects, such as chalking, browning, and bleaching, indicating that these bubbles are distinct from those usually observed. [Display omitted] •Visual inspection was carried on PV modules that operated for 30 years in Algeria.•Bubbles formation observed only in fingers of the PV cells.•Shape and a location rarely observed for these bubbles.•Bubbles formation, chalking and browning are linked by a single phenomenon.•Bubbles are probably the results of an electrochemical reaction involving oxygen.