# DC Building Network and Storage for BIPV Integration

Author(s) Hofer, Johannes, Svetozarevic, Bratislav, Nagy, Zoltan, Schlüter, Arno
Publication Type Conference Contributions, Publication Status: Published
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Title DC Building Network and Storage for BIPV Integration
Author(s) Hofer, Johannes
Svetozarevic, Bratislav
Nagy, Zoltan
Schlüter, Arno
Editor(s) Scartezzini, Jean-Louis
Book Title Proceedings of International Conference CISBAT 2015 Future Buildings and Districts  Sustainability from Nano to Urban Scale
Start Page 681
End Page 686
Publisher CISBAT
Publication Place Lausanne
Publication Date 2015
Keyword(s) Building integrated photovoltaics (BIPV)
DC network
Energy efficiency
Electricity storage
Self-consumption
Net-zero energy building
Abstract Electricity loads in buildings are increasingly supplied by distributed renewable generation sources such as photovoltaic (PV) modules or fuel cells. Often these systems are combined with an electricity storage to raise the level of self-consumption in buildings and to reduce the load on the electric grid. PV production and battery storage are both inherently based on direct current (DC) power. At the same time, an increasing number of energy-efficient devices that are part of the building service systems – such as LED’s, electronic equipment, or variable speed motors for efficient operation of ventilation units and heat pumps – use DC internally. Consequently, direct coupling of PV generation with electricity storage and DC loads in a local DC network has the potential to avoid power conversion losses arising in conventional alternating current (AC) based systems. In addition to the more efficient use of local generation and storage, an independent building micro-grid can provide system reliability in case of power outage.
In this work, we perform a first evaluation of potential efficiency gains of low-voltage DC versus AC distribution in residential buildings with PV generation and battery storage. We take into account high-resolution electric load and PV generation profiles for a net-zero energy building. We find that relative to a conventional AC system, a DC network improves energy efficiency by approximately 2% without storage and 4% with storage. Moreover, we analyse the sensitivity of the results to variations in PV system size and battery characteristics. We show that the benefit of the DC system becomes more significant with increasing local generation and storage and that energy efficiency improvement and building self-sufficiency are correlated. The theoretical analysis provides guidance for a lab-scale hardware implementation of a small AC/DC hybrid system, which is currently in preparation.
DOI 10.5075/epfl-cisbat2015-681-686
Event Name International Conference CISBAT 2015 on Future Buildings and Districts - Sustainability form Nano to Urban Scale
Event Location Lausanne, Switzerland
Event Date September 9-11, 2015
Document Type Conference Paper
Publication Status Published
Language English
Assigned Organisational Unit(s) 03902
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Source Database ID FORM-1450099470
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@inproceedings{Hfr2015,
author = "Hofer, Johannes and Svetozarevic, Bratislav and Nagy, Zoltan and Schl{\"{u}}ter, Arno",
editor = "Scartezzini, Jean-Louis",
title = "{D}{C} {B}uilding {N}etwork and {S}torage for {B}{I}{P}{V} {I}ntegration",
booktitle = "Proceedings of International Conference CISBAT 2015 Future Buildings and Districts  Sustainability from Nano to Urban Scale",
year = 2015,
pages = "681--686",