Photovoltaic Modules Repair: Application Case of Spot-Welding in Junction Box Bussing Ribbons

In the context of photovoltaic (PV) module repair and reuse, this work is an extent of previous research [1], where a testing procedure is proposed and circa 1000 c-Si based PV modules were diagnosed and classified to identify those with repairable faults. Failures were categorized by module areas, including the junction box (jbox), backsheet, frame, external electrical conductors, and connectors. Within the jbox, tin soldering that connects bussing ribbons to the main electrical busbar often melts due to overheating. This study analyzes the application of the spot-welding technique to repair these connections. Three different application techniques were simulated by computational rendering to determine the ease of application, considering the nickel plates and tools manipulation. The selected welding technique implies a horizontal coating of the bussing ribbon, folding it and covering it with a double folded nickel plate. The PV modules with faulty jbox are subjected to electrical characterization (I-V curves, electrical resistance) before and after the module restoration. The repairs were also evaluated by injecting DC current into the PV modules to monitor adverse reactions and hot-spots emergence in the new welds. The procedure is deemed effective, as the thermal patterns showed no development of hot-spots and the PV modules get their electrical output restored. This work contributes to the circular economy of the PV sector, validating the spot-welding method as a tool to refurbish broken electrical connections inside a PV module jbox.