Influence of an insulation partition on a seeded directional solidification process for quasi-single crystalline silicon ingot for high-efficiency solar cells

Abstract

An insulation partition was designed in a seeded directional solidification (DS) furnace of industrial-size to produce quasi-single crystalline silicon ingot for solar cells of high efficiency. We used a transient global model to study the effects of the insulation partition block on the temperature and thermal stress fields in the solidified silicon ingot during the solidification process. We validated the transient global model by comparing the calculations with the experimental measurements. Simulation results show that an insulation partition block can significantly reduce the total heating power consumption and influence the temperature and velocity fields in the silicon melt. We also found that the melt-crystal interface (m–c interface) shape changes from concave to convex to the melt with a larger crystal growth rate with an insulation partition, while it always remains flat with a smaller crystal growth rate without a partition block. The axial temperature gradient and thermal stress in the grown silicon crystal increased with a partition block. The solar cells from the grown quasi-single crystalline silicon ingot exhibited higher short-circuit current (Isc) and open-circuit voltage (Voc). The average conversion efficiency of solar cells is increased to 17.8% and about 1.2% more than that based on mc-Si ingot from the conventional furnace.