NOVELTY - The thermal storage tank comprises multiple heat transfer units connected to one side of a metal plate, a thermoelectric element connected to other side of the metal plate, and a thermal energy storage material installed at one side of a housing. The thermal energy storage material: stores heat from an outside panel through a solid-liquid phase change of 110-130 degrees C; and includes sodium nitrate, potassium nitrate, lithium nitrate and/or magnesium nitrate. The tank further comprises: a cooling device that is installed at one side of the thermoelectric element and comprises a cooling pin.    USE - The thermal storage tank is useful in a solar power generation system (claimed).    ADVANTAGE - The thermal storage tank is capable of rapidly absorbing the heat and then maintaining the absorbed heat for long period of time without any heat loss thus improving solar energy utilization efficiency and solar power generation efficiency of the generation system.    DETAILED DESCRIPTION - The thermal storage tank comprises multiple heat transfer units connected to one side of a metal plate, a thermoelectric element connected to other side of the metal plate, and a thermal energy storage material installed at one side of a housing. The thermal energy storage material: stores heat from an outside panel through a solid-liquid phase change of 110-130 degrees C; and includes sodium nitrate, potassium nitrate, lithium nitrate and/or magnesium nitrate. The tank further comprises: a cooling device that is installed at one side of the thermoelectric element and comprises a cooling pin; a cooling fan for providing airflow through the cooling pin; a cooling plate in which a cooling pipe provides a cooling fluid in an inner portion of the tank; and a control unit for measuring the temperature of the first and second spaces using first and second sensors, where the first sensor locks a valve of a first supply tube, and the second sensor locks a valve of a second supply tube. The cooling plate is connected to other side of the thermoelectric element. The thermoelectric element includes matrix-type thermoelectric cells. The housing includes first and second spaces, and a partition wall for distinguishing the spaces. A heat exchanger is installed on the first space, and heats a heat transfer medium that is installed at coaxial outside of the heat exchanger for transferring thermal energy to the tank. The cooling device cools the thermoelectric element.