Abstract: A bulk thermal energy storage device is provided comprising a bulk storage tank containing a latent energy storage material, preferably a phase change material which is subject to repeated melting and freezing during which latent thermal energy is absorbed or released by the phase change material. A plurality of heat exchange devices are generally vertically positioned within the phase change material and at a predetermined distance from each other and from the walls of the storage tank for flow of a heat exchange fluid serially through said passageways in the heat exchange devices. At least one screen is positioned in the storage tank in a generally horizontal position and extending between the walls of the tank and the heat exchange devices for supporting the phase change material when in a frozen condition during the melting cycle of the phase change material to prevent settling of the phase change material to the bottom of the tank.