Making Better Use of On-Site PV Generation: Direct Distribution of DC Power in Buildings

Stephen Frank, Rich Brown, Lester Shen, Vagelis Vossos, Daniel Gerber

Research output: NRELPoster


With the increasing availability of Direct Current (DC) power from on-site solar systems, building designers now have the option of direct distribution of DC power to energy storage systems and end-use loads such as lighting, electronics, and motors. Research shows that direct-DC can reduce building distribution losses by 5-15%, while improving power reliability. A readily available way to implement direct-DC distribution is Power over Ethernet (PoE), which typically has provided low-voltage DC to power office equipment such as WiFi access points. With recent updates to the PoE standard, equipment such as network-controlled LED lighting, thin client and computer workstations, HVAC controllers, fans, motors, and actuators can now be powered by PoE and are commercially available. This paper presents results from a DOE-funded project that is demonstrating PoE technologies and describes a DC modeling and design tool that is intended to help building designers properly evaluate and design DC distribution systems in buildings. The tool provides designers of DC power systems with estimates of both power system losses and indirect effects on building heating and cooling. The results of this research demonstrate that the design methods and products are available to implement DC power in buildings today.
Original languageAmerican English
StatePublished - 2019

Publication series

NamePresented at the ASES Solar 2019 Conference, 5-9 August 2019, Minneapolis, Minnesota

NREL Publication Number

  • NREL/PO-5500-74447


  • direct current modeling
  • direct distribuiton
  • energy storage
  • power in buildings
  • reliability


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