Posted on March 30, 2011

Why PG&E Didn’t Propose a Wired SmartMeter™ Option

Over the past several months, PG&E has reviewed several alternatives to its radio frequency (RF) based SmartMeters™ in order to respond to some customers’ concerns that RF-communications might be harmful. That analysis necessarily took into account several competing factors: customers’ concerns, the cost of creating a parallel infrastructure, state and national advancement of a modernized smart grid, and the technical feasibility of any alternative.

Last week, PG&E proposed what it views as the best alternative available for customers with concerns about SmartMeters™:  the option to have the radios in their SmartMeters™ turned off, eliminating all RF-communications to and from their meters.

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Some have asked why PG&E didn’t propose an option with a wired meter.  PG&E did consider that alternative, and determined it was neither technically available today nor economically feasible.

Two wired solutions are available today.  The first, called power line carrier (PLC) technology, uses power lines to transmit data to and from the meters.  The other uses traditional phone lines.  After a careful assessment, PG&E resolved that neither of these is feasible.

Independent experts can confirm this.  As Erich Gunther, chairman and CTO of Enernex, an electric power engineering and consulting firm, wrote on his blog: “PG&E has made a reasonable response.”  Gunther is the chairman of the Energy Department’s GridWise Architecture Council, and also is a member of PG&E’s SmartMeter™ Technology Advisory Panel.

Here’s why PLC, technologies won’t work:

  • No PLC technologies exist for gas meters.  So, even if PG&E implemented a wired solution for electric meters, another infrastructural approach – and the associated costs to customers of providing it – would still be necessary.
  • No PLC technologies can effectively be integrated with PG&E’s existing RF-mesh network at a reasonable cost.
  • Some utilities have used PLC technologies as an alternative to an RF network . An end-to-end powerline carrier solution would require PG&E to add equipment at each electric substation throughout Northern and Central California, even if PG&E were only to serve one customer from each substation.  The cost to purchase and install this equipment could be hundreds of thousands of dollars per substation.  Other hybrid PLC solutions such as interconnecting to the RF-mesh would require a significant investment for infrastructure that would be extremely expensive.   In this hybrid solution, it would require equipment at as many as 1 million distribution transformers, and significant back office integration costs.

“PG&E correctly points out that integrating a nearly obsolete PLC-based wired option with a modern wireless infrastructure would be costly since it requires equipment at each substation even if only one customer were served,” Gunther wrote.

Here is why traditional telephone-wire technologies won’t work:

  • No telephone-wire technologies exist for gas meters.  So, even if PG&E implemented a wired solution for electric meters, another infrastructural approach – and the associated costs to customers of providing it – would still be necessary.
  • PG&E has 19,000 MV-90 (phone line) meters, and the company isn’t aware of any existing MV-90 system that scales beyond 30,000 meters. Since PG&E must offer this alternative to perhaps 150,000 customers or more – it’s unknown exactly how many customers might seek a wireless SmartMeter™ alternative, but PG&E’s research suggests perhaps 150,000  – and since a system that scales to that size doesn’t exist, this solution isn’t feasible.
  • A telephone-line option is substantially more expensive than PG&E’s proposed radios-off option.  Commercial-grade, MV-90 modem-based meters exist, but they cost several thousand dollars apiece, and PG&E isn’t aware of existing, proven residential-grade meters that are wired for a telephone connection.
  • Connecting a meter to a telephone service would require an additional cost.
  • A telephone-wire meter technology would not support Home Area Network devices or the smart-charging of electric vehicles.

Gunther noted that telephone-based systems are “difficult to scale.”  Plus, he said, those phone lines are rapidly being replaced in favor of cellular phone networks.

For those who have suggested wiring a DSL line directly to a meter or using a customer’s home internet service to capture usage data, these solutions are not yet commercially available.  PG&E continues to engage the industry to ensure that the company is positioned to evaluate and test new technologies as they emerge in the market. Although they may eventually become available, customers have asked PG&E to respond to their concerns as quickly as possible, and PG&E’s proposing a solution that does not yet exist would be unreasonable.

PG&E will continue to work with the CPUC and its customers to provide answers about SmartMeter™ technology.  One good resource is the company’s SmartMeter™ webpage:  www.pge.com/smartmeter.

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"PG&E" refers to Pacific Gas and Electric Company, a subsidiary of PG&E Corporation.
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