Effects of Cu wire’s shape on the plating property of Sn-Pb solder for photovoltaic ribbons

We studied the plating properties of Sn-Pb solder according to the shape of the Cu wire's cross-section for photovoltaic ribbon. The thickness of the Sn-Pb layer largely decreased to 29% on a curved Cu surface, compared to a flat Cu surface. This phenomenon is caused by the geometrical decrease in the contact angle of the liquid Sn-Pb solder and an increase in the surface energy of the solid/vapor on the curved Cu surface. We suggest a new ribbon's design where the Cu wire's cross-section is a semi-ellipse. These semi-ellipse ribbons can decrease the use of Sn-Pb solder to 64% and increase the photovoltaic efficiency, by reducing the contact area between the ribbon and cell, to 84%. We also see an improvement of reflectivity in the curved surface.