Solder paste for module fabrication of solar cells

A method of fabricating a solar module by interconnection of a plurality of photovoltaic (PV) cells in which at least a first PV cell is interconnected to a second PV cell using an electrically-conductive adherent comprising or consisting of a solder paste;

• the solder paste comprising particles of solder alloy dispersed in a solder flux;
• wherein the solder alloy comprises from 48 to 51 wt. % Bi, from 0.7 to 1.1 wt. % Cu, from 0.02 to 0.09 wt. % Co, from 0.8 to 1.1 wt. % Ag, and the balance being tin together with any unavoidable impurities, and wherein the solder alloy has a liquidus temperature of less than 225° C.;
• wherein the solder flux comprises:
• from 25 to 40 wt. % of a rosin and/or a resin,
• from 12 to 20 wt. % of an activator,
• from 10 to 20 wt. % of a surfactant, and
• from 20 to 40 wt. % of a solvent;
• wherein the solar module comprises a back-contact assembly in which a rear face of the first PV cell is directly interconnected with a rear face of the second PV cell by one or more ribbons, wherein the one or more ribbons are connected to the rear face of the first PV cell and the rear face of the second PV cell using the electrically-conductive adherent comprising or consisting of the solder paste;
• and
• wherein the solder paste is stencil printed or jet printed.