NOVELTY - Preparing a polycrystalline silicon ingot, comprises: paving seed crystals on a bottom of a container in a polycrystalline silicon ingot growing furnace to form a seed crystal layer; loading solid silicon raw materials above the seed crystal layer; heating the container, smelting the silicon raw materials and part of the seed crystal layer to form a liquid layer, and keeping a part of the seed crystal layer contacted with the bottom of the container in a solid state; and controlling a thermal field in the polycrystalline silicon ingot growing furnace.    USE - The method is useful for preparing polycrystalline silicon ingot, which is useful for a solar cell (claimed).    ADVANTAGE - The method allows economical preparation of polycrystalline silicon ingot with low impurity content and attenuation coefficient and high photoelectric conversion efficiency.    DETAILED DESCRIPTION - Preparing a polycrystalline silicon ingot, comprises: paving seed crystals on a bottom of a container in a polycrystalline silicon ingot growing furnace to form a seed crystal layer, where the seed crystal layer is formed by paving a large single crystal seed crystal of which the size and the shape are the same as those of the bottom of the container, splicing small single-crystal seed crystals, or paving blocky plate blanks cut from polycrystalline silicon main bodies; loading solid silicon raw materials above the seed crystal layer; heating the container, smelting the silicon raw materials and part of the seed crystal layer to form a liquid layer, and keeping a part of the seed crystal layer contacted with the bottom of the container in a solid state; and controlling a thermal field in the polycrystalline silicon ingot growing furnace, and crystallizing the liquid layer to form a crystallizing layer to ensure that a solid interface moves toward the direction far away from the bottom of the container to finish the growth of polycrystalline silicon ingot. An INDEPENDENT CLAIM is included for a solar cell made from the polycrystalline silicon ingot, comprising: a wafer with a continuous and large-size monocrystalline silicon region having a same crystallographic orientation; a P-N junction in the wafer; and a conductive contact placed on the wafer.    DESCRIPTION OF DRAWING(S) - The figure shows a flow chart of a method for preparing polycrystalline silicon ingot (Drawing includes non-English language text).