Smart Grid Tech Take: Is Silver Spring Networks' "SEN" the Breakthrough We've Been Waiting for?

Date of Tech Take: January 16, 2008

In SGN's Tech Take articles, power engineer and architect Erich Gunther evaluates actual products and services against the SGN Smart Grid Scorecard. Unless disclosed explicitly at the beginning of the article, neither SGN nor Erich Gunther has received any compensation from the vendor nor do they own stock in the company.

This article examines the Smart Energy Network, a collection of products from Silver Spring Networks (SSN) that create a network infrastructure for Smart Grid applications. Although it has shortcomings, I believe Smart Energy Network could be a breakthrough product. To understand my evaluation, you need to grasp three essential elements:

·         The role of the SGN Scorecard

·         The purpose and components of a network infrastructure

·         How Smart Energy Network measures up

The role and importance of the SGN Scorecard

The SGN Scorecard was developed for a very important reason: most of today's products do not adhere to Smart Grid principles. They do not support the requirements envisioned by Smart Grid researchers such as EPRI, the California Energy Commission's Public Interest Energy Research program, the Modern Grid Initiative and DOE's GridWise program. Nor do they adhere to the mandates in the Energy Independence and Security Act of 2007. 

In particular, several elements of the EPRI IntelliGrid Architecture are critical to implementing a Smart Grid:

·         Proven, Internet derived communication technologies

·         Service based architecture at the enterprise level

·         Self healing technology

·         Well defined interfaces and points of interoperability

·         Application of industry and international standards

·         Built in security and network management

As a result of their failure to meet the basic principles, most of today's communication networks -- whether for automatic meter reading (AMR) or for advanced meter infrastructure (AMI) -- are inadequate. They may support "least common denominator" Smart Grid applications such as meter reading. But they are not adequate for distribution automation, plug in hybrid electric vehicle management, microgrids, demand response and many other future applications.

SGN Warning: To avoid buying dead-end products, utilities must provide their vendors with a comprehensive and prioritized list of requirements covering current and future functionality. And then they must get written assurances from vendors that their products meet those requirements.

The SGN Scorecard is a checklist that measures whether products meet minimum standards for a Smart Grid. We will use it as the benchmark for all Tech Talk reviews. You are invited to use it free of charge for your own evaluations. For a further explanation and a blank version you can copy freely, download the PDF version of the Scorecard.

The purpose of a network infrastructure

In a network infrastructure, multiple components form a backbone. That backbone provides core functions. Other products build on top of that backbone to create applications. The basic components of a network infrastructure are:

1.       The end points that connect to devices such as meters, sensors and thermostats

2.       The access points that a) link together to create a neighborhood network and b) talk to the backhaul network

3.       The network operating system and network management software

4.       The backhaul communications that carries data to and from the control center

Typically, the first three components are provided by one vendor. Ideally, those first three components will be able to use any of several different backhaul "pipes." Indeed, one of the hallmarks of a good network infrastructure is to be "communications agnostic" -- that is, to use any of several different systems to get the data back to the utility's enterprise software.

SSN's product lineup

SSN's Smart Energy Network (SEN) consists of components that, taken together, provide end-to-end Internet Protocol-based connectivity from the field devices (meters, thermostats, substation and feeder equipment) all the way to the utility enterprise. Those components include

·         Intelligent Endpoints -- radio cards for meters (and eventually for other devices)

·         Relay SG -- a standards-based router that relays signals (passes them along) to extend the reach of the neighborhood network

·         Access Point SG -- a network access point that links end points to the utility's enterprise software

·         UtilOS -- network operating system

·         UtilityIQ -- network management software

Together, these components create the network infrastructure for a wide variety of Smart Grid applications. SEN was recently deployed at Florida Power & Light. It has the potential to scale up to 100,000 meters at FPL, which would make it one of the largest IP-based AMI networks in the country.

Evaluating the components

Let's look at some individual components before scoring the entire suite. Relay-SG product is notable for allowing the network to be readily extended. It creates a robust mesh architecture with numerous routing paths. Translation: The signal from one end point can take many different paths to get to the access point and from there to the enterprise. If one path is problematic due to a poor signal, the end point can probably find another route instead.

I have learned that early experience from the Florida Power & Light rollout indicates a very high packet success rate for SEN. Other key metrics are also being achieved. (I understand that SSN will publish results at DistribuTech in mid-January, 2008.)

Next up is the Access SG product. It forms neighborhood area networks using 900 MHz wireless mesh technology.  See our related article about the differences between the 900 MHz and 700 MHz spectrum. Access SG is noteworthy for its ability to connect to a wide range of backhaul communications infrastructures both public and private.

Finally, the UtilOS and UtilityIQ network software provide a rich set of standards-based interfaces (XML and SOAP) to enterprise applications such as customer billing, distribution automation and outage management.

How SEN measures up against the competition

Overall, SEN scores very well against the EPRI IntelligGrid Architecture elements and SGN's Smart Grid Scorecard. (Scroll down for the final score.) I have been impressed with SSN’s commitment to the standards process. The firm is deeply involved in the IETF, the IEEE, the IEC, OpenAMI, UtilityAMI, AMI-SEC and other standards bodies. Because of its support for open standards, SEN can easily add new applications, making it cost effective and "future proof.”

In particular, SEN incorporates more industry communications standards than its competitors. SEN uses the latest mesh network RF technology and Internet standards (XML, SOAP, TCP, IPv4 and IPv6) to provide a highly scaleable and robust network infrastructure. And SEN is among the first wireless network technologies to fully embrace end-to-end IP-based connectivity. That includes use of the IPv6 standard, which eliminates limitations on the number of unique device addresses. It appears that SSN’s competitors will be incorporating IPv4 and/or IPv6 soon, so all utilities should now require this in their communications protocols. 

To be sure, competitors such as Cellnet+Hunt and DCSI TWACS have more mature products in the field. Yet the SGN Smart Grid Scorecard shows that SEN is more capable of hosting the full suite of applications necessary to truly implement a robust, intelligent and efficient electric grid.

Where SEN and others still fall short

Like most of its competitors, SEN still needs to improve interoperability between vendor products and interface cards.  Vendors need to standardize on an RF mesh network technology (including routing protocols and performance metrics) so there is interoperability between products. Such standards will allow utilities to mix-and-match solutions from multiple vendors. That approach reduces cost and avoids getting locked into one vendor.

A second issue is the need to standardize the physical, electrical, and information exchange interfaces between the communications provider and the meter. Presently, each communication vendor develops a unique interface card for each meter (in close cooperation with the meter vendor).  This one-at-a-time, custom approach presents a high barrier of entry for new meter vendors. That's good for meter vendors perhaps, but not for the utility customers. Put bluntly, utilities will not see lower meter prices until there is more competition. The UtilityAMI organization has noted this as a high priority with significant value to utilities.

SEN Smart Grid Scorecard: 81 out of 100

Metric	Score (10 is best)	Comments
Impact	8	Supports a wide range of Smart Grid applications
Openness	6	Reference designs and source code escrow allow flexible vendor implementation. However, the core RF technology is proprietary
Standardization	8	IP-based technology, XML/SOAP enterprise interfaces and a commitment to further standardization in the RF mesh
Security	9	Security has been built into the core using robust, proven technology. Some improvement still needed
Manageability	8	IIP-based technology allows the use of readily available network management tools
Upgradeability	8	All firmware remotely upgradeable over the network in a short time frame
Scalability	6	Scalability is designed in but remains to be proven in the field
Extensibility	10	The modular nature of mesh networking inherently provides extensibility
Self-Healing	10	Mesh networks are inherently self-healing and SSN employs additional techniques to minimize network recovery time from outages
Interactivity	8	Based on UtilIQ enterprise application and web interface functionality
Total	81	Every utility should take a close look at SEN before choosing its platform for Smart Grid applications.
Date of product: July 2007. Access SG has the following part number and revision: Part Number: SSN-DS-AccessPt-SG Rev. 7/07 The gas meter endpoint and other core components have the same release date on their technical data sheets. SSN has separate end-point products for each major meter vendor. We have not evaluated each of these products independently as the only variation is the interface with the vendor.

SEN claims to create an extensible network infrastructure suitable for deploying a wide range of Smart Grid applications, and to do so independent of underlying technology details. Our Scorecard generally confirms this claim. Given these results, SEN could be a groundbreaking communications solution.

Erich W. Gunther is Chairman of EnerNex Corporation. He chairs the UtilityAMI / OpenHAN standards group and serves on the GridWise Architecture Council.

   Email Erich W. Gunther

   Smart Grid Scorecard (PDF)

   EPRI IntelliGrid Architecture Web site

   GridWise Architecture Council

   Silver Spring Networks Web site

   Cellnet+Hunt Web site

   DCSI TWACS Web site