Provided is a method of managing distributed energy resources (DER) and a device for performing the method. A system for managing distributed energy resources includes a memory configured to store instructions, and a processor electrically connected to the memory and configured to execute the instructions, and when the instructions are executed by the processor, the processor is configured to determine at least one DER that is to supply power to a consumer from among a plurality of DERs, using a rank of each of the DERs indicating importance as a power source supplying power to the consumer and information about power consumed by the consumer.