Advanced front side metallization for crystalline silicon solar cells based on a nickel-silicon contact

Silicon solar cells were metalized on the front side using plated nickel-silicon contacts. Nickel is used as a seed layer for silver LIP, or simultaneously used as a seed and diffusion barrier for copper LIP. Suitable plating techniques and parameters were determined, using electroless nickel and tin, and light induced plating of nickel, silver and copper. Solar cell efficiencies 17.4% on CZ industrial-type material (5x5cm²) have been achieved for a two step nickel-silver metallization, and 17.1% for a nickel-copper-tin stack. Long term stability limitations due to copper diffusion with respect to 5%rel degradation have been evaluated by a method developed in our labs. A cell life time limitation well exceeding several hundred years was estimated.