NOVELTY - A polysilicon ingot is manufactured by spreading (S101) seed crystal at bottom of container in polysilicon ingot growth furnace and forming seed crystal layer, loading (S102) solid state silicon raw material above seed crystal layer, heating (S103) container, smelting silicon raw material and part of seed crystal layer and forming liquid layer, controlling (S104) thermal field in polysilicon ingot growth furnace, and re-melting and crystallizing (S105) and obtaining polysilicon ingot.    USE - Manufacture of polysilicon ingot for solar cell (claimed).    ADVANTAGE - The method manufactures polysilicon ingot with low impurity.    DETAILED DESCRIPTION - A polysilicon ingot is manufactured by spreading (S101) seed crystal at bottom of container in polysilicon ingot growth furnace and forming seed crystal layer; loading (S102) solid state silicon raw material above seed crystal layer; heating (S103) container, smelting silicon raw material and part of seed crystal layer and forming liquid layer while holding part of seed crystal layer contacted to bottom of container as solid state; controlling (S104) thermal field in polysilicon ingot growth furnace, crystallizing liquid layer to form crystallizing layer to move solid-liquid interface far away from bottom of container; and re-melting and crystallizing (S105) after moving corresponding distance in direction far away from bottom of container from solid-liquid interface and obtaining polysilicon ingot after performing process of re-melting and crystallizing once. The process of re-melting and crystallizing involves controlling thermal field in polysilicon ingot growth furnace to re-melt crystallizing layer, enabling solid-liquid interface to move in direction near bottom of container, and controlling thermal field in polysilicon ingot growth furnace to crystallize liquid layer to enable solid-liquid interface to move in direction far away from bottom of container. The distance of solid-liquid interface moving in direction near bottom of container is less than distance of solid-liquid interface moving in direction far away from bottom of container. INDEPENDENT CLAIMS are included for:    (1) polysilicon ingot; and    (2) solar cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the manufacturing method of polysilicon ingot. (Drawing includes non-English language text).    Spreading process of seed layer (S101)    Loading process of solid silicon raw material (S102)    Heating process of container (S103)    Controlling process of thermal field in polysilicon ingot growth furnace (S104)    Re-melting and crystallizing process (S105)