Combining design of experiments and power loss computations to study the screen printing process

The screen printing process applied to the front side metallization of silicon solar cell was studied with a full factorial 3²4¹6¹ design of experiments on an industrial line. Four commercially silver pastes from different suppliers, six apertures, and nine stainless screens were used to analyze the printing results of two hundred and sixteen combinations. The fingers geometrical properties, the line resistivity, and the contact resistivity were inputted in a power loss simulation program to compute the optimal fingers spacing and the theoretical efficiency for each combination. The relative contribution and the effect of all factors and interactions on the solar cell efficiency were calculated to find out general guidelines for process optimization. Finally, a confirmation test was performed on mixed batches of 15.6 × 15.6 cm², 200 μm thick Cz-Si solar cells to validate assumptions. With an optimized process a maximal 19.2 % efficiency was reached.