NOVELTY - Preparing polycrystalline silicon ingot comprises placing or coating a highly pure material onto container bottom of a polycrystalline silicon ingot growing furnace to form an isolative and protective layer, paving seed crystals on isolative and protective layer to form a seed crystal layer, loading a solid silicon raw material on seed crystal layer, heating container to smelt silicon raw material and seed crystal layer to form a liquid layer, keeping seed crystal layer contacted with isolative and protective layer in a solid state, controlling thermal field and crystallizing liquid layer.    USE - The polycrystalline silicon ingot is useful for preparing solar batteries.    ADVANTAGE - The polycrystalline silicon ingot: has many monocrystalline silicon regions and isolative and protective layers, which reduces the impurity content in the polycrystalline silicon ingot; and increase the photoelectric conversion efficiency of the solar batteries made from the polycrystalline silicon ingot.    DETAILED DESCRIPTION - Preparing polycrystalline silicon ingot comprises placing or coating a highly pure material onto the container bottom of a polycrystalline silicon ingot growing furnace to form an isolative and protective layer, paving seed crystals on the isolative and protective layer to form a seed crystal layer, loading a solid silicon raw material on the seed crystal layer, heating the container to smelt the silicon raw material and the seed crystal layer to form a liquid layer, keeping the seed crystal layer contacted with the isolative and protective layer in a solid state, controlling the thermal field in the polycrystalline silicon ingot growing furnace and crystallizing the liquid layer to move the solid-liquid interface away from the container bottom until the completion of polycrystalline silicon ingot growth. INDEPENDENT CLAIMS are also included for:    (1) a polycrystalline silicon ingot prepared by the above mentioned method, where continuous and large-sized monocrystalline silicon regions are present according to the crystallographic orientation; and    (2) a solar battery, comprising a wafer on which the continuous and large-size monocrystalline silicon zones with accordant crystallographic orientation are arranged, where P-N nodes and conductive contactors are located in the wafer.