An approach is provided for a method to manufacture a crystalline silicon ingot. The method comprises providing a mold formed for melting and cooling a silicon feedstock by using a directional solidification process, disposing a barrier layer inside the mold, disposing one or more silicon crystal seeds on the barrier layer, loading the silicon feedstock on the silicon crystal seeds, heating the mold to obtain a silicon melt, and cooling the mold by the directional solidification process to solidify the silicon melt into a silicon ingot. The mold is heated until the silicon feedstock is fully melted and the silicon crystal seeds are at least partially melted.