The pastes presented in this paper contain metal powder with a particle size 0.5 μm < dpart < 5 μm, glass frits
and an organics composition optimized to the particles. A certain amount of the silver particles in this paste is
replaced by a base metal to reduce the silver content without jeopardizing the sintering process. With the optimized
pastes, we produce 150 cells with neighboring wafers for cell efficiency measurements with two types of rear bus
bar paste, varying the amount of silver. The cells are produced in a conventional production line, taking
conventional front paste and a conventional rear aluminum. The cells are co-fired with parameters optimized for
the reference paste.