Cell Performance Prediction based on the Wafer Quality

Among many other parameters, wafer quality plays an important role in determining the efficiency of a solar cell and the power output of a module. Researchers have spent a lot of efforts in developing new casting methods to produce low-cost high-quality multicrystalline Si wafers. However, multicrystalline Si ingot technology is, still at this stage, a crystallization process that is difficult to control and produces silicon wafers with a wide range of quality. There is a rising need to develop in-line techniques to accurately assess wafer quality. In this paper, a new wafer characterization method is presented and the results of research to find the correlation between wafer quality and cell performance are reported. Based on the analysis of photoluminescence (PL) of as-cut wafers, and taking the cell process into account, a new method to predict the cell efficiency is demonstrated. The objective of the proposed method is to be able to sort, with a simple in-line technique, multicrystalline as-cut wafers for the reason that high- quality wafers are more suitable for high efficiency processing.