From high‐efficiency n‐type solar cells to modules exceeding 20% efficiency with aluminum‐based cell interconnection

Abstract

We present the integrated development of back-contacted solar cells and an adequate module interconnection for a highefficiency photovoltaic module. We report on a large area (125 Â 125) mm 2 back-junction back-contact n-type solar cell metallized with aluminum having a total area conversion efficiency of 20.7%. To transfer the high conversion efficiency to the module, we use the laser welding process named aluminum-based mechanical and electrical laser interconnection for module integration of these back-contacted solar cells. We further analyze the impact of the busbars of our back-junction back-contact cells on the cell performance and report on optimization of the cell/module interface. The new cells have an adapted rear-side geometry by omitting the emitter busbar. A proof-of-concept module consisting of these cells is presented.

Interconnection of busbar‐free back contacted solar cells by laser welding

“…In general, the metallization geometry of the solar cell features an interdigitated finger structure and busbars collecting the current from the individual fingers. Simulations and measurements have shown that the busbar regions of the BJBC solar cells reduce the fill factor and short-circuit current density [5][6][7]. Other extended structures like contact areas with several tens of square millimeters cause similar problems.…”

“…In this work we are presenting the module integration of busbar‐free BJBC solar cells by means of a simplified multilevel metallization. We contact each individual base and emitter finger to an Al foil using the aluminum‐based mechanical and electrical laser interconnection (AMELI) process . A polymer layer insulates the base from the emitter metallization.…”

“…A polymer layer insulates the base from the emitter metallization. In addition to the module integration process, we are presenting modifications to our previously reported baseline BJBC cell process . These modifications enable busbar‐free interconnection.…”