Cost-Performance Analysis for Interdigitated Back-Contact Solar Cells Using Ion Implantation Process

Abstract

The back-contact crystalline solar cell features a design in which the positive emitter and negative back surface field are both located on the rear surface. The obvious benefit of this design is that efficiency can be improved by eliminating shading from the front metal grid. However, fabricating devices with the conventional back contact configuration requires costly patterning. The high manufacturing costs and complexity of the patterning process has been a barrier in preventing the solar cell industry from adopting the back-contact design despite it having the highest conversion efficiency. To reduce costs and the number of processes, we fabricated interdigitated back-contact solar cells using an ion implantation process with a shadow mask instead of the conventional patterning and diffusion process, and achieved a 22.9% conversion efficiency. To analyze the cost-performance of ion implantation process, we developed a bottom-up cost model involving five categories: depreciation expenses, materials, labor, utility, and maintenance costs assuming a production of 300 MW/year. The reduction in process steps using ion implantation substantially decreased the initial capital expenses. This impacted the overall cost structure and reduced the cell processing costs by 20% compared to conventional back-contact solar cells.