This report presents the results of a scoping study conducted to identify options and approaches to sub-metering of residential loads, distributed generation, and storage. Utility interest in this subject has increased, driven by the employment of residential solar photovoltaic systems as well as the potential for significant consumer adoption of plug-in electric vehicles (PEVs) in the near future and battery storage options in the longer term. For a variety of reasons, some utilities may find it necessary to sub-meter these new technologies, as well as traditional end-uses such as water heating and electric thermal storage (ETS). Presently, utilities do not have many options for addressing these sub-metering needs, and most simply place an additional meter socket and standard ANSI meter for each additional sub load. This approach works with what is presently available, but may not be the most attractive or lowest-cost metering option.
This scoping study explores if better options might exist, such as those made practical by the creation of new or modified metering devices and standards. The study was carried out through broad stakeholder engagement in a series of three workshops, focused on metering/advanced metering infrastructure (AMI), solar photovoltaics (PV), and electric transportation. In each workshop, participants brainstormed various plausible approaches for sub-metering, describing each in diagram form and through the identification of their capabilities and limitations. In some cases, sub-metering may be considered primarily for billing purposes (“utility grade metering” or “billing grade metering”). In these cases, the range of potential sub-metering methods may be smaller. However, this scoping study looked beyond billing applications to include those methods that might be found useful for verification, approximation, load research, or strictly informational purposes.