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Soldering Challenges in Multibusbar Interconnection Assembly
N.S. Pujari, J. Sundaramurthy, S. Sarkar, C. Bilgrien
New Materials and Concepts for Photovoltaic Devices
Subtopic: New Materials and Concepts for Cells and Modules
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 1BV.3.52
ISBN: 3-936338-60-4
0,00 EUR
Document(s): poster


Tabbing and stringing is the dominant method in the market for making crystalline silicon (c-Si) solar cells modules. Soldering ribbons are used as an interconnection medium in this process on the four or five busbars of the front- and back-side metallization. The process is well established and provides desired reliability to the modules. However, for crystalline silicon solar cell, the challenges to obtain cost-effective solar electricity include low-cost manufacture of high-quality large area crystalline silicon wafers, reduce the amount of silver (Ag) paste per cell without losing efficiency and stability, reduce electrical and optical losses; and implementation of simple and low-cost processing in conjunction with advanced cell architectures to achieve efficiency of over 22%. Multi busbar (MBB) technology promises to alleviate some of the above problems. The technology was first introduced in 2012 and over a period of time, several approaches to achieve MBB interconnection have been emerged [1]. Soldering, low temperature alloy lamination (Smart wire), woven fabrics assisted soldering and the prefabricated interconnected grid method (Merlin) etc. are to name few. Among them, the MBB technology of soldering is the closest to the traditional cell interconnection technology. The current module equipment can be upgraded to assemble MBB modules. Schmid company was the first one to develop a special stringer machine for MBB modules. Now, several Chinese equipment manufacturers are developing this kind of machines. Typically, MBB cells are interconnected by seven to fifteen solder coated copper wires with circular cross section (Diameter between 200 and 430 μm) on each side of the solar cell. The wires are soldered by infrared soldering on silver pads printed on the front and back of the cells.