TY - JOUR

T1 - Novel busbar design for screen-printed front side Al metallization of high-efficiency solar cell

AU - Schulte-Huxel, Henning

AU - Daschinger, Thomas

AU - Min, Byungsul

AU - Brendemühl, Till

AU - Brendel, Rolf

N1 - Funding Information: This work was funded by the state of Lower Saxony and the Federal Ministry for Economic Affairs and Climate Action (BMWK) under grant number 03EE1012A (NanoPERC) and 03EE1150A (Apolon).

PY - 2024/1

Y1 - 2024/1

N2 - The need to reduce the silver consumption for future global PV production requires novel approaches for cell metallization and module integration. A screen-printed aluminum cell metallization on the front side could contribute here, but requires a redesign of the solder pads and busbars. A compromise between shading and resistive losses is needed. We investigate the inclusion of Ag solder pads in high-aspect-ratio Al finger grids on the front side of p-type back junction solar cells featuring passivating polysilicon on oxide (POLO) contacts on the rear side. In order to determine the optimal geometric dimensions of the solder pads, we characterize the resistance at the interface between the Ag solder pads and the Al finger grid in dependence on the size of the overlap between the two paste. A contact resistance of 285 mΩ is determined for 200 μm-narrow Al busbars and small solder pads of 750 μm in length. This would require tens of solder pads per busbar for acceptable power losses below 0.5 % coming along with significant shading. Therefore, a new metallization design is developed. We use narrow Ag busbars with a widened intersection to the Al fingers in order to reduce the contact resistance caused by the Ag–Al alloy. Thereby, the shading losses of the solderable busbars and pads are less than 1.5 %.

AB - The need to reduce the silver consumption for future global PV production requires novel approaches for cell metallization and module integration. A screen-printed aluminum cell metallization on the front side could contribute here, but requires a redesign of the solder pads and busbars. A compromise between shading and resistive losses is needed. We investigate the inclusion of Ag solder pads in high-aspect-ratio Al finger grids on the front side of p-type back junction solar cells featuring passivating polysilicon on oxide (POLO) contacts on the rear side. In order to determine the optimal geometric dimensions of the solder pads, we characterize the resistance at the interface between the Ag solder pads and the Al finger grid in dependence on the size of the overlap between the two paste. A contact resistance of 285 mΩ is determined for 200 μm-narrow Al busbars and small solder pads of 750 μm in length. This would require tens of solder pads per busbar for acceptable power losses below 0.5 % coming along with significant shading. Therefore, a new metallization design is developed. We use narrow Ag busbars with a widened intersection to the Al fingers in order to reduce the contact resistance caused by the Ag–Al alloy. Thereby, the shading losses of the solderable busbars and pads are less than 1.5 %.

KW - Al metallization

KW - Busbars

KW - Module integration

KW - Photovoltaic module

KW - Silver-free

KW - Solar cell interconnection

UR - http://www.scopus.com/inward/record.url?scp=85174936446&partnerID=8YFLogxK

U2 - 10.1016/j.solmat.2023.112601

DO - 10.1016/j.solmat.2023.112601

M3 - Article

AN - SCOPUS:85174936446

VL - 264

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

SN - 0927-0248

M1 - 112601

ER -