Automation in HEM silicon ingot production [for solar cells]

A fully automated heat exchanger method (HEM) furnace has been used to produce 55 cm square cross section, 155 kg, multicrystalline silicon ingots with precise control, uniformity and consistency. Operator involvement was limited to loading and unloading of the furnace. With a cycle time of 48 hours, the installed capacity for such a furnace is 1.75 MW/year on production basis. Solar cells up to 18.6% (1 cm/sup 2/) efficiency have been fabricated.