Interconnection 1, 2, 3, 4.0: Buildup towards a PV Technology Hero?

Abstract

In this paper an overview of interconnection technologies for bifacial and back-contacted (bifacial) cells in different stages of their development is reported, leading to a new technology suited for efficient interconnection of (bifacial) back-contact cells. BACKGROUND: MERGING CELL AND MODULE DESIGN In the field of c-Si PV interconnection, interest in more efficient interconnection technologies with high aesthetical value is steadily growing, to catch up with the impressive efficiency progress at cell level during the last years, now nearing the fundamental limits for cells based on crystalline Si as absorber [1]. This interest is being translated in an increasing number of busbars for cell interconnection, culminating in the introduction of multi-wire interconnection technologies [2]. With such an approach, the optical performance is improved by reducing effective shading area and the generated electrons are extracted more efficiently out of the cell. This relaxes the requirements for the cell metallization and cell doping and results in reduced electrical losses and/or metallization cost. To get the most out of such an approach, the cell (metallization) and interconnect scheme should be meticulously co-designed. As the production for such 2-side contacted (and bifacial) cells and interconnection technologies is rather close to the industry standard, it can be implemented relatively straightforward. Next to this trend, a revival of (also bifacial) back-contacted cell technologies is seen, thanks to recent breakthroughs in efficiencies [3] and cost reductions in materials and process steps. Though further away from current industrial focus, the promising potential of such cells raises a need for efficient and cost-effective interconnection technology. Given the increased complexity for cell metallization compared to 2-side contacted cells (patterning and alignment steps), and higher process and material costs of metallization on cell level and cell insulation, there is an even greater interest to relax requirements on cell metallization level as much as possible and shift it to the interconnection level. With an overview of our holistic approach in developing such interconnection technologies for both 2-side-and back-contacted cells, this paper