Directional solidification platform for polysilicon cast ingot

The utility model relates to the field of solar battery manufacturing, in particular to a directional solidification platform for a polysilicon cast ingot. The directional solidification platform is hexahedral, the top surface and the bottom surface of the directional solidification platform are square, and the side surfaces are rectangular. The directional solidification platform is characterized in that the bottom surface of the directional solidification platform is a concave curved surface indented to the middle; a distance between a vertex of the concave curved surface and the top surface is 0.5d-0.8d; and d is width of the side surfaces of the directional solidification platform. The platform is simple in structure; the bottom surface is designed as the concave curved surface indented to the middle, so that a transverse isothermic gradient of crystalline silicon is smaller in an initial nucleation area of crystal growth; a longitudinal temperature gradient is greater; the generation probability of crystal grains in the nucleation area is increased; overall dislocation density of the silicon ingot is reduced; and silicon wafer battery conversion efficiency is improved.