The University of New South Wales (UNSW), together with SunDrive and Shenzhen APG, partially substituted silver powder with nickel powder in the rear-side metallization of TOPCon solar cells, achieving a 6.8% reduction in raw-metal cost for rear fine-grid fingers (about US$561,500/GW) with almost no impact on cell efficiency. The findings were disclosed to pv magazine by corresponding author Ning Song. The experiments were based on two commercial nickel powders, Ni-1500 and Ni-4000. The team formulated five rear-side pastes containing 90% metal powder, 2% glass frit, and 8% organic vehicle. Using pure silver paste as the baseline, the other four pastes incorporated 5% to 15% nickel into the metal powder, using Ni-1500 with a particle size of about 1.5 μm and Ni-4000 with about 3.8 μm. The pastes were screen-printed onto 182 mm × 183.75 mm n-type TOPCon cells, then dried, co-fired at a peak set temperature of 724 C, and treated with laser-enhanced contact optimization (LECO). Each formulation covered at least 12 cells and was run across two industrial production lines. Results showed that the finer Ni-1500 powder, with higher specific surface area and oxygen content, caused greater resistive loss at the same nickel loading: at 5% loading, efficiency remained at the baseline of 26.349%; at 10% loading, it dropped to 26.124%, a decrease of 0.225 percentage points. In contrast, the 10% Ni-4000 formulation reached 26.325% efficiency, only 0.024 percentage points below the baseline. Microscopic analysis showed that high-loading Ni-1500 formulations had more voids and poorer silver network continuity. Nickel substitution also increased printed fine-grid finger width and paste consumption, and at higher loadings the additional paste consumption offset part of the expected benefit. The study did not involve metal additive manufacturing or powder-bed processes, and the news item mentioned no other direct connection to 3D printing powder applications.