A mathematical investigation of the impact of gridline and busbar patterns on commercial silicon solar cell performance

Abstract

The cost and efficiency of solar generation are two parameters that must be optimized if it is to replace fossil-fuel sources in the electricity production market. Since the single-junction cell structure still holds the promise of cost-effectiveness and simple production, it is imperative to find ways to increase the efficiency above 20% in production. A comprehensive empirical grid model is first established herein to investigate front grid designs with three, four, and five busbars, the results of which are compared with numerical analysis using Griddler 2-D modeling software. It is found that a combination of segmented tapered metal grids (SG) and uneven busbars (UEB) leads to an increased short-circuit current density (JSC) and open-circuit voltage (VOC) without sacrificing the fill factor. The five-busbar SG–UEB combination results in efficiency above 20% for industrial-sized solar cell without an additional step or layer. The improvement in the cell efficiency obtained using the uneven busbar design is attributed not only to the decreased shading but also to reduced contact recombination underneath the busbars. In addition to increasing the efficiency, the results show that the cost of the front Ag metallization for each cell can be reduced by 1.4¢ per cell by using the presented segmentation method.