Researchers from Univ. Grenoble Alpes, CEA, Liten, and Univ. Paris Est Créteil have studied copper (Cu) pastes as alternatives to silver (Ag) for metallizing silicon heterojunction (SHJ) solar cells. Ag is costly and scarce, making Cu a potential substitute. The tested Cu-based cells showed lower overall performance than Ag or Ag/Cu pastes. However, no silicon defects from Cu were detected, even after 40 minutes of annealing at 200°C. Cu pastes had comparable contact resistivity to Ag, with better results under certain annealing conditions. High line resistance (Rline) in Cu remained a concern. Microscopy revealed smaller Cu line areas, partly explaining performance gaps. Annealing under argon reduced Rline by 60%, but performance stayed below Ag pastes.