A smart server and smart device are disclosed, by which a new power unit price (hereinafter named a combined power unit price) can be calculated in consideration of an internally generated electricity quantity instead of using an external power unit price as it is. The present invention includes a power demand obtaining unit obtaining a home power demand for at least one electronic appliance including a smart device, a generated quantity detecting unit detecting an internally generated power quantity for at least one home generator, a price information receiving unit receiving power information including external power price information on an external power via a network, and a combined unit price output unit outputting a combined power unit price using an external power demand and the internally generated power quantity and the external power price information, wherein the external power demand is calculated based on the power demand.