Mark McGranaghan: Meters ... Maybe

This posted to smartgrid@ostp.gov by Mark McGranaghan , EPRI

Q1: The most capable and cost effective means for delivering usage, price, and demand response signals to devices in customer premises will differ by locale and will evolve with time as technologies change and penetration levels increase for home Internet connectivity and public wireless cellular connectivity. This may or may or may not be a smart meter. The best means of delivering information will also depend on the particular information. For instance, delivering real-time energy use information to a particular customer has different requirements than delivering price information or demand response information that may be the same for a broad group of customers. Regardless of the means of communicating information, it is important that there is national industry consensus on messaging formats to enable multiple options for communicating the data and not preclude one option over another.

Factors to consider when making an assessment of whether or not to use a smart meter as a primary gateway include:
• Meters are generally not accessible by homeowners or non-utility service personnel
• Meters are dangerous to remove and install and result in an outage to the premise when removed
• Meters have traditionally provided effective service lives of 20 years or more. This is an important consideration because communication and computing based technologies have been evolving at a much faster rate than the service life of an electric meter.

However, it is possible that meters could be the most economic means of implementing gateways for functions like demand response (e.g. controlling smart thermostats or water heaters), especially in the initial deployment stage. This has the advantage of assuring the availability of participation in the programs across the customer base, regardless of the availability of other infrastructure. Since these programs can effectively involve control of customer equipment, it is also important that appropriate security policies are implemented as part of the system.

This logic can extend to a broader range of gateway functions if no other option is available or economic. In these cases, utilities have utilized their metering communication systems to reach the home and provide gateway functions.

Q2: It is very reasonable to expect that any, or all, of the data types identified in question 1, (i.e. usage, price, and demand response signals) may be provided to devices in the home via some means other than a gateway in the meter. As suggested in the response to question 1, the meter is essentially an option of last resort for providing this information but one that may be economical and appropriate if other options are not available.

It is, however, unnecessarily limiting, to consider that the other means for providing this data must be a “gateway”, if this term implies a bridge to a second network inside the home prior to reaching the end device. Home Area Networks are one architectural option, but not a necessary one. Historically, utilities have used pager systems, FM radio data broadcasts, public cellular, and long-range power-line carrier signals to deliver information directly to end-use devices.

Q3: There are many different architectures that can be employed for providing energy use and demand response (pricing or other signals related to needs for energy management) information to consumers and thereby help enable open innovation in home energy services.

For price or demand response information, there are many architectures by which this information can be made known to devices in the home, including wide area broadcast (pager, PLC, FM), direct utility network (RF mesh, tower, etc), and broadband connection (community wireless internet, advanced cellular, cable, and DSL). In some cases, it may be desirable to include indications of local reliability events (local overload, circuit capacity limitations, etc.) in the demand response information and this puts additional requirements on the messaging to communicate with targeted resources (e.g. this may be more difficult to do with widespread broadcast of the information since different signals are required for different customers).<

Usage information, unlike price, can be acquired by the consumer from a smart meter or from other devices with the capability to monitor energy use. While the utility meter provides premise-level data, it is not a normal function to collect submetered information for individual circuits and/or devices in the home.

There is one aspect of usage data that only utilities can provide and that is usage as it relates to the customer billing period. For example, a display in the home could present to the customer their cumulative bill (in dollars) thus-far in the month along with a projection of what the total bill would be if consumption should continue at the same pace. This useful and motivational information could be calculated by utility systems and then provided to consumer systems using the same range of communication options previously listed.

Architectures that support innovation in home energy services are essentially unlimited. Examples of architectural elements that are possible:

• Verified price and consumption data is provided to the home via Internet from the utility, data from the electric meter is included.
• Same as 1 but usage data comes from customer or end-device meters.
• Same as 1 except usage data was collected to the utility office in real-time over the utility’s network prior to being provided to the home.
• Verified price information is provided via the Internet, usage data is provided as interval data updated twice a day.
• Price is transmitted via FM radio, usage data direct from the local meter.
• Price is a repetitive TOU schedule, locally computed from a schedule provided months ago.