mc-Si: Relation Between Ingot Quality and Cell Efficiency

摘要

We have investigated and compared material properties and solar cells of several common multicrystalline ingots. Apart from the contaminated end parts of the ingots the cell quality correlates well with the as-received lifetime, and the lifetime profile through the ingot correlates with the distribution of defect densities in the material. The asreceived lifetime after light soaking is a reasonable predictive parameter for cell performance for the complete ingot if the major impurity in the end parts is iron, and if the oxygen concentration is low. A high oxygen concentration of 15-20 ppma in the bottom parts of some ingots, instead of the more common 5-10 ppma for that position, correlates with a strong reduction of cell efficiency.