Eddy-Current Analysis Method for Non-Destructive Characterization of Electrical Contacts and Solder Joints in PV Modules

According to latest studies, cell and interconnection failures are to most common ones besides backsheet and encapsulation issues in PV modules. Solder joints within the module, which are not meeting the target quality, often lead to major issues after aging, comprising burn marks, hotspots, arcing discharges and of course substantial power losses. Besides security and safety issues, such age-related effects can lead to major financial losses for manufacturers, investors and plant owners. Within the Austrian flagship project “Sustainable Photovoltaics”, a nondestructive method was developed for analyzing the quality of solder joints in PV modules (on site & in production line) using a multi frequency eddy current approach. With the presented solution the conductivity of each solder joint can be analyzed, enabling the possibility of early failure detection, and hence initiating possible repair approaches. Measurement results show that the calculated state or conductivity decrease of aged solder joints can be successfully correlated to electroluminescence (EL) images. This enables a solder joint quality analysis without, unlike EL, directly powering the PV module.