Energy Efficiency and Cost Performance of Direct-Current Power Supply Systems in Residential Buildings by 2030s and 2050s

Gyuyoung Yoon,Saya Yoshioka,Shinji Sakai,Kyoko Sugiyama,S.I Tanabe,M.C Gameiro Da Silva,H Zhang,I Nastase,C Inard,J Kurnitski,G Cao,P Wargocki,L Mazzarela

doi:10.1051/e3sconf/201911104010

Abstract

In an effort to clarify the potential use and effectiveness of direct current (DC) power supply systems and further promote their usage, this study investigates the energy saving and cost performance characteristics of such a system for a detached house equipped with roof-mounted solar photovoltaic (PV) panels. Our evaluation considered different DC-powered appliances under different energy price conditions and made projections based on present, 2030s, and 2050s scenarios. Initial cost reductions were also considered based on assumed near-future technological developments. Our case study results show that the simple payback period is likely to be shortest in cases where DC power is only used for low-voltage appliances under present price conditions, when supplying DC power to cover interior space heating under the 2030s energy price scenario, and when covering all DC-powered appliances (including water heating) under the 2050s scenario. Taken together, these results indicate that it is desirable to set the introductory targets while projecting future energy price fluctuations and anticipating the cost reductions that will result from ongoing technological developments.

Highlights

Because the promotion of energy conservation in private dwellings has emerged as one of the more important methods for reducing greenhouse gas emissions, the net zero-energy-house (ZEH) concept has drawn significant attention in recent years
In this paper, based on the consideration that PVgenerated direct current (DC) power can be applied to detached houses in various ways, we evaluate various scenarios based on the range of the DC-powered devices and electric energy flow, as well as the primary energy consumption, initial costs, running costs, and the simple payback periods for each scenario
Based on the estimation results, we found that DC power supply system under the current situation is an exorbitant solution if there are no subsidies or political advantages to using it

Summary

Introduction

Because the promotion of energy conservation in private dwellings has emerged as one of the more important methods for reducing greenhouse gas emissions, the net zero-energy-house (ZEH) concept has drawn significant attention in recent years. A ZEH would achieve fundamental energy conservation targets, including a zero-energy balance, by extensive use of renewable energy. Various technologies have been proposed to facilitate energy conservation in houses, including passive measures to suppress heat loads and active measures to improve energy utilization efficiency. As a means to promote renewable energy utilization, the spread of solar photovoltaic (PV) power generation has been significantly expanded in Japan due to the implementation of the feed-in-tariff (FIT) scheme. It is thought that the usefulness of such systems will increase further as PV power generation systems spread, even though DC power supply systems are still under development

Objectives

Results

Conclusion