Consumer Portal is defined as combination of hardware and software that enables two-way communication between energy service provider(ESP, like KEPCO) and equipment within the consumer`s premises. The portal provides both a physical link(between wires, radio waves, and other media) and a logical link(translating among language-like codes and etiquette-like protocols) between in-building and wide-area access networks. Thus, the consumer portal is an important, open public shared infrastructure in the future vision of energy services. In this paper, we describe a new methodology for local communication and computer network capacity design of consumer portal, and also presents capacity calculation method using a network system limitation factors. By the approach, we can check into the limitations of existing methods, and propose an improved data processing algorithm that can expand the maximum number of the networked end-use devices up to times. For validation, we applies the proposed methode to our real system design. Our contribution will help electrical power information network design.