Near-Contactless Production I-V Testing of Silicon Solar Cells

We demonstrate a new tool capable of performing nearly contactless current-voltage (I-V) and efficiency measurements for binning in silicon solar cell production lines. We validate the technique against conventional test methods for over 400 cells representing a range of technologies including 5-busbar passivated emitter rear contact (PERC), 5-busbar heterojunction technology (HJT), and both 9-busbar and 16-busbar tunnel oxide passivated contact (TOPCon). The tool leverages a wide variety of metrology techniques including Suns-Voc, light I-V, dark I-V, and a series resistance (Rs) analysis based on a single photoluminescence (PL) image. The Rs analysis reports multiple key resistive loss components including grid/finger loss (Rgrid) as well as the combined effect of emitter and contact loss (Rcontact). The technique is designed especially for present and future cell concepts (e.g. “multi-busbar” and “busbarless” cells) that use minimal silver and are thus difficult to electrically probe for standard I-V characterization.