“Bidirectional metering is where the modern grid becomes visible. It records not only what a customer consumes, but also what that customer contributes back to the system.” – MJ Martin
Introduction
Bidirectional electric meters are increasingly important as the electric grid evolves from a one-way delivery system into a more dynamic network of customers, generators, storage systems, and distributed energy resources. Traditional electric meters were designed to measure electricity flowing from the utility to the customer. A bidirectional meter must do more. It must measure electricity flowing in both directions, including energy consumed from the grid and energy exported back to the grid.
Meters made by companies such as Itron are often configured with multiple register channels, sometimes described in the field as three radios or three ERT channels. In practical terms, these channels allow the utility to collect separate metering values for different billing and operational purposes.
Delivered Energy
The first and most common channel is delivered energy, usually measured in kilowatt-hours. Delivered energy is the electricity that flows from the utility grid to the customer. This is the normal consumption value used for standard residential, commercial, and industrial billing.
For a customer without generation, delivered energy may be the primary value required for billing. It tells the utility how much electricity the customer consumed during the billing period. This value is also useful for usage history, energy reporting, load forecasting, and customer service inquiries.
In a bidirectional application, delivered energy remains essential because even customers with solar panels or small wind generators still consume electricity from the grid at certain times. At night, during cloudy periods, during low wind conditions, or when site demand exceeds generation, the customer still imports electricity from the utility.
Received Energy
The second channel is normally received energy. This is the electricity that flows from the customer back to the utility grid. It is especially important for customers with solar photovoltaic systems, small wind turbines, battery storage systems, or other forms of distributed generation.
When a customer generates more electricity than they are using at that moment, the excess energy flows backward through the meter and into the distribution system. The meter records this exported energy as received kilowatt-hours. This does not automatically mean the customer is being paid like a power plant. The meter only measures the energy flow. The utility tariff, regulator, and local program rules determine whether that exported energy becomes a credit, an offset, or a payment.
The Third Channel
The third channel depends on the utility’s metering configuration and billing requirements. In many bidirectional residential applications, the third value may be net energy. Net energy is the difference between delivered energy and received energy. This value can be useful for net metering programs where the customer’s imported and exported energy are reconciled for billing.
In commercial applications, the third channel may instead be peak demand, measured in kilowatts. Demand is important because some customers are billed not only for how much energy they use, but also for the highest rate at which they draw power during a billing interval. In other applications, the third channel may represent reactive energy, time-of-use energy, or another specialized register.
Why Separate Channels Matter
Separate channels are important because a single net value does not tell the full story. A customer who imports 1,000 kilowatt-hours and exports 700 kilowatt-hours has a net use of 300 kilowatt-hours. Another customer may simply use 300 kilowatt-hours and export nothing. The net result appears the same, but the operational meaning is very different.
By separating delivered, received, and net or demand values, the utility gains better visibility into actual energy flows. This supports accurate billing, distributed generation settlement, transformer loading analysis, feeder planning, and revenue protection.
Solar, Wind, and Grid Export
Bidirectional meters are directly used for solar and wind customers who export electricity to the grid. They provide the measurement foundation for net metering, feed-in tariffs, buyback programs, and other distributed generation arrangements.
The meter does not decide the financial arrangement. Its job is to accurately measure electricity moving in both directions. The utility’s billing system then applies the applicable rules. This is why the three-channel structure is so valuable. It gives utilities and customers a transparent record of what was consumed, what was exported, and what value should be used for billing or settlement.
Summary
Bidirectional electric meters are essential tools for the modern power grid. Their multiple channels allow utilities to measure delivered energy, received energy, and a third billing or operational value such as net energy or demand. For solar and wind generation, these measurements are critical because they document both customer consumption and exported generation. As distributed energy resources become more common, bidirectional metering will continue to be a core requirement for fair billing, grid management, and energy transparency.
About the Author:
Michael Martin is the Vice President of Technology with Metercor Inc., a Smart Meter, IoT, and Smart City systems integrator based in Canada. He has more than 40 years of experience in systems design for applications that use broadband networks, optical fibre, wireless, and digital communications technologies. He is a business and technology consultant. He was a senior executive consultant for 15 years with IBM, where he worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He is a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN: TSX).
Martin served on the Board of Directors for TeraGo Inc (TGO: TSX) and on the Board of Directors for Avante Logixx Inc. (XX: TSX.V). He has served as a Member, SCC ISO-IEC JTC 1/SC-41 – Internet of Things and related technologies, ISO – International Organization for Standardization, and as a member of the NIST SP 500-325 Fog Computing Conceptual Model, National Institute of Standards and Technology. He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) [now Ontario Tech University] and on the Board of Advisers of five different Colleges in Ontario – Centennial College, Humber College, George Brown College, Durham College, Ryerson Polytechnic University [now Toronto Metropolitan University]. For 16 years he served on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section.
He holds three master’s degrees – in business (MBA), communication (MA), and education (MEd). As well, he has three undergraduate diplomas and seven major certifications in business, computer programming, internetworking, project management, media, photography, and communication technology. He has completed over 80 next generation MOOC (Massive Open Online Courses) [aka Micro Learning] continuous education programs in a wide variety of topics, including: Economics, Python Programming, Internet of Things, Cloud, Artificial Intelligence and Cognitive systems, Blockchain, Agile, Power BI, Big Data, Design Thinking, Security, Indigenous Canada awareness, and more.
Martin in a volunteer, a photographer, a learner, a technologist, a philosophizer, and a romantic optimist.