First systems architecture draft for the UH-HNEI | US DoE EERE SunShot Initiative Grid, Photovoltaic & Battery Smart Grid Inverter Project - A nascent smart grid communications protocol standard for embedding a high-penetration of residential PV inverters on existing electrical distribution networks.

1. Silver Spring Networks
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Redwood City, CA 94063
www.silverspringnet.com
UH-HNEI Smart Grid Inverter Project
System Architecture

2. Confidential and Proprietary 20 May 2013 Silver Spring Networks 2
System Architecture Contents
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®
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®
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trademarks, trademarks, or service marks of their respective owners.
Revisions
Version Date Change
1.0 8 August 2012 Final customer draft

3. Confidential and Proprietary 20 May 2013 Silver Spring Networks 3
System Architecture Contents
Contents
Contents 3
1.
Introduction...................................................................................................................................... 4
1.1.
Overview .....................................................................................................................................4
1.2.
Glossary - Acronyms...................................................................................................................4
2.
Smart Grid Inverter (SGI) System Architecture ............................................................................... 5
2.1.
Smart Grid Inverter (SGI) System Architecture Overview...........................................................5
2.2.
Phase 1: SGI Virtual Environment ..............................................................................................5
2.3.
Phase 2: SGI Integrated Environment ........................................................................................6
2.4.
Phase 3: SGI Embedded Environment .......................................................................................7

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System Architecture Introduction
1. Introduction
1.1.Overview
The Systems Architect Diagram shows a progression from simple to more complex reference
architectures for usage in the development and testing of smart grid inverter communication
specifications. Implementation of these specifications is for integration of high-penetration
residential photovoltaic (PV) systems into pre-existing electrical distribution networks.
1.2.Glossary - Acronyms
Acronym Definition
802.15.4 IEEE Standard for Low Rate WPAN
CIQ Consumer IQ
AGF Advance Grid Functionality
DER Distributed Energy Resources
ESI Energy Services Interface
HAN Home Area Network (ZigBee IP + SEP 2.0)
HTTP/REST Hypertext Transmission Protocol/Representational State Transfer
IP Internet Protocol
NAN Neighborhood Area Network (900 MHz RF Mesh)
NIC Network Interface Controller
PV Photovoltaic
RF Radio Frequency
RS422 Recommended Standard 422 (Serial Interface Standard)
SEP 2.0 Smart Energy Profile 2.0
SoW Statement of Work
SSN Silver Spring Networks
TCP/IP Transmission Control Protocol/Internet Protocol
UH-HNEI University of Hawai’i – Hawai’I Natural Energy Institute
VM Virtual Machine
WAN Wide Area Network
WPAN Wireless Personal Area Network

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System Architecture Smart Grid Inverter (SGI) System Architecture
2. Smart Grid Inverter (SGI) System Architecture
2.1. Smart Grid Inverter (SGI) System Architecture Overview
A representation of the UH-HNEI Smart Grid Inverter System Architecture for high-penetration PV
applications solution is presented in this section. The architectural development process is a
phased approach progression in virtual, integrated and embedded environments. This approach
improves hardware design and software debugging, allowing acceleration of the deployment of the
embedded system.
This architecture framework includes inter-operability, modular components and key attributes
including scalability and reliability.
The System Architecture Diagram shows the reference architectures among Head End, Energy
Services Interface (ESI) and the Inverter in the system being modeled. The System Architecture
Diagram is illustrated in Figure 1 and Figure 2. These diagrams may evolve throughout the
development process in Phase 2 (Integrated Environment) and Phase 3 (Embedded Environment).
All updates to be included in the deliverables associated with Silver Spring Networks Statement of
Work (SSN SOW) Tasks 1.2a and 1.3a.
2.1.1. Head End
The Head End is the originating point in a communications system; in this case it is the utility. The
Silver Spring Networks Customer IQ (SSN CIQ) web portal is used by the utility. The SSN CIQ is
comprised of Distributed Energy Resource (DER) programs and controls that are sent to the ESI via
a wide area network (WAN) and network area network (NAN).
2.1.2. ESI (Energy Services Interface)
The ESI is comprised of a Silver Spring Network Interface Controller (SSN NIC) programmed with
firmware running the Zigbee IP and Smart Energy Profile 2.0 (SEP 2.0). The ESI communicates
DER control functions to the Inverter.
2.1.3. Inverter
The Inverter is a device that converts variable direct current from a PV array into a utility frequency
alternating current. This device is to be fitted with an Embedded Linux Board running the Zigbee IP
and SEP 2.0, providing monitoring and control of the DER.
2.2. Phase 1: SGI Virtual Environment
Phase 1 was comprised of a virtual, proof-of-concept net metering schema. [Not shown]

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System Architecture Smart Grid Inverter (SGI) System Architecture
2.3. Phase 2: SGI Integrated Environment
The Integrated Environment is comprised of the Head End, ESI and Inverter.
The Head End, the electric power company, uses the SSN CIQ web portal back office software to
communicate via a wide area network (WAN) running the Hypertext Transmission
Protocol/Representational State Transfer (HTTP/REST) protocol to the ESI. The ESI enables
secure interactions between the WAN using HTTP/REST, and to the Inverter via an RS422
interconnection.
The ESI is comprised of a Linux Router running the SSN NIC firmware on an Embedded Linux
Board running SEP 2.0 End Device DER Metering program. The Linux Router communicates by
Ethernet via HTTP/REST with the WAN. The Embedded Linux Board communicates SEP 2.0 End
Device Distributed Energy Resource (DER) Metering control functions to the Inverter via an Inverter
Interface Library using the interconnection standard RS422.
A representation of the Integrated Environment, which includes special production hardware that
has been successfully implemented on a virtual machine (VM), follows:
NB: The RS422 interconnection standard is being updated with the RS485 standard. The following
diagram represents the present state of the system, and may evolve over the course of SSN SoW
Task 1.2.
Head
End
Inverter
Ethernet
PV
Metering
And
Control
System
Administration
TCP/IP
v6
CIQ
WAN
HTTP/REST
Linux
Router
TCP/IP
v6
Ethernet
Ethernet
SEP
2.0
ESI
HTTP/REST RS422
Embedded
Linux
Board
Ethernet
SEP
2.0
End
Device
DER
Metering
TCP/IP
v6
Inverter
Interface
Lib
Integrated
Environment
Phase
2
Figure 1. Integrated Environment - Inverter Deployment to the Integrated Environment [SSN SoW Task 1.2]

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System Architecture Smart Grid Inverter (SGI) System Architecture
2.4. Phase 3: SGI Embedded Environment
The Embedded Environment is comprised of the Head End, ESI and Inverter.
The Head End, the electric power company, uses the SSN CIQ web portal back office software to
communicate via Ethernet to a wide area network (WAN). The WAN runs the Hypertext
Transmission Protocol/Representational State Transfer (HTTP/REST) protocol via an Access Point
to a neighborhood area network (NAN). The ESI enables secure interactions between a
neighborhood area network (NAN) and home area network (HAN), both running the HTTP/REST
protocol.
The ESI is comprised of SSN NIC firmware running the SEP 2.0 ESI program. The SSN NIC
communicates via a 900 MHz mesh to the NAN, and via the interconnection IEEE Standard
802.15.4 with the 2.4 GHz HAN.
The Inverter fitted with an Embedded Linux Board communicates SEP 2.0 End Device Distributed
Energy Resource (DER) Metering control functions to the ESI via interconnection IEEE Standard
802.15.4 to the HAN.
A representation of the Embedded Environment for deployment in the field, which includes special
production hardware, follows:
NB: The following diagram represents the present state of the system, and may evolve over the
course of SSN SoW Task 1.3.
Head
End
Inverter
Ethernet
PV
Metering
And
Control
System
Administration
TCP/IP
v6
CIQ
NAN
HTTP/REST
Embedded
Environment
Phase
3
Access
Point
TCP/IP
v6
900
M
Hz
Ethernet
Embedded
Linux
Board
802.15.4
SEP
2.0
End
Device
DER
Metering
ZigBee
IP
Inverter
Interface
Lib
SSN
NIC
SEP
2.0
ESI
900
M
Hz
802.15.4
TCP/IP
v6
ZigBee
IP
HTTP/REST
HAN
2.4
GHz
WAN
HTTP/REST
Figure 2. Embedded Environment - Inverter Deployment to the Embedded Environment [SSN SoW Task 1.3]