Detailed 3D full-cell modeling in Quokka3: Quantifying edge and solder-pad losses in an industrial PERC cell
A multidomain approach is proposed and applied to model an industrial 15.6×15.6 cm2 PERC cell in 3D in full-size. An inner cell domain and two edge domains are chosen as irreducible symmetry elements, each containing the unequal front and rear pitch, the dashed rear contacts, and part of the busbars. The full-cell current is determined by a simple summation instead of a distributed network model, as the metal resistance is accounted for in the large 3D domains. The approach is implemented in Quokka3 which automatically constructs the domains from the full-cell properties and can solve them in practical computing times. Production-line PERC cells from Tina Solar are reproduced with measured input parameters. From this, two full-cell effects are quantified: i) the influence of rear solder-pads on cell performance, and ii) the edge losses under various conditions. We find that even though the rear-solder pads are relatively wide compared to the front busbars, their impact on efficiency is negligible, unless a severe degradation of the passivation quality is present. Edge losses can be in the order of up to 0.2 %abs efficiency due to edge recombination, and the edge distance should be held below 1 mm.