Fourth-generation high efficiency polycrystalline technology: Based on the existing high purity raw materials and all molten, semi-melt process of efficient polycrystalline, the improvement of ingot furnace structure helps reduce the lateral temperature difference in the furnace to get a flatter, longer grain boundary, a better column crystal and a lower concentration of silicon ingot. At the same time, DS special heat conduction makes the liquid fully convection to reduce impurity deposition. The improvement of ingot end achieves 0.1 % improvement in battery efficiency and improve its quality and efficiency.