Energy storage module for battery rack comprisng phase change material heat exchanger

An energy storage cooling system for an energy storage module has a chiller for supplying a coolant; a PCM heat sink including a heat exchanger; a piping system for circulating the coolant between the chiller, the heat exchanger and a battery rack of the energy storage module; a valve system including at least one 3-way valve arranged upstream to the PCM heat sink and to the battery rack; a control unit configured to control the 3-way valves in different operating modes including at least following modes: Battery cooling mode, wherein the coolant is allowed to circulate through PCM heat sink and through the battery rack; and battery heating mode, wherein the coolant is not allowed to circulate through PCM heat sink but allowed through the battery rack.