Manufacturing metrology for c-Si module reliability and durability Part II: Cell manufacturing

This article is the second article in a three-part series dedicated to reviewing each process step in crystalline silicon (c-Si) photovoltaic (PV) module manufacturing process: feedstock and wafering, cell fabrication, and module manufacturing. The goal of these papers is to identify relevant metrology techniques that can be utilized to improve the quality and durability of the final product. The focus of this article is on the cell fabrication process. In this review, the fabrication of c-Si PV cells is divided into four steps: (1) wet chemical processes; (2) emitter formation; (3) anti-reflection coating (ARC) and passivation deposition; and (4) metallization. Each of these processing steps can impact the final reliability and durability of PV modules deployed in the field, and here the failure modes and degradation mechanisms induced during cell manufacturing are explored. Additionally, a literature review of relevant measurement techniques aimed at reducing or eliminating the probability of such failures occurring is presented along with an assessment of potential gaps wherein the PV community could benefit from new research and demonstration efforts.