A Paradigm Shift for Utility Load Management?

Posted to EPRI in the Utility Management Group
image credit: The software-integrated energy management circuit breaker could potentially enable a utility to monitor and control the load on a transformer from EV charging in a residential neighborhood.
Thomas Reddoch's picture
Principal Technical Executive, Electric Power Research Institute (EPRI)

Dr. Thomas Reddoch is a Senior Technical Executive at EPRI. His program management responsibilities include Energy Efficiency, Demand Response, Electric Transportation, Distributed Generation...

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  • Sep 30, 2020

The growing numbers of electric vehicles (EVs) and other distributed energy resources on distribution systems are challenging the traditional utility approach to load management. Historically, utilities have sized transformers in residential and commercial areas so they can reliably serve customers’ peak load, adding extra capacity to handle unexpectedly high energy use. One residential transformer is usually sufficient to service two to eight houses. But what happens when a few of the residential customers served by a transformer purchase an EV and then connect an EV charger?

“The load pattern changes and can exceed the capacity of the transformer, causing it to potentially overload,” said EPRI Principal Technical Executive Tom Reddoch.

These customer purchases pose a potential dilemma for utilities. Upgrading a transformer to accommodate a significant new load can be expensive. And waiting until a transformer overloads and needs to be replaced is both expensive and inconvenient for customers who lose power until new equipment is installed.

There is another emerging option that gives utilities the flexibility to manage EV charging and other loads in a way that meets the needs of customers without costly transformer upgrades or risking a blackout. EPRI is evaluating a system that combines novel software developed by Virtual Peaker with an energy management circuit breaker (EMCB), a device installed in a residential or commercial circuit breaker panel. This system continuously monitors voltage, current, power, and other attributes of energy use by various appliances in a house or business, enabling utilities to control each appliance’s consumption.

Developed by Eaton Corporation, the EMCB can be configured with a secure WiFi communication network and connected via the cloud to the software. Eaton has completed development of an EMCB for use with loads such as HVAC equipment, water heaters, pool pumps, batteries, and other loads. A second EMCB designed specifically for EVs is under review for safety certification by Underwriter Laboratories (UL) and is expected to be ready for testing in 2021.

The Virtual Peaker software standardizes the format of the energy use data as well as the power management commands from utilities and customers. For example, if a thermostat reports a room’s temperature in Celsius, the software may convert the data to Fahrenheit.

“The software integrates with internet-connected thermostats, water heaters, EV chargers, residential battery systems, and the EMCB and streams real-time data into a cloud-based platform,” said William Burke, CEO of Virtual Peaker. “If the data is in a standardized format, utilities don’t have to worry if it’s coming from a water heater made by General Electric or an EV charger made by ChargePoint.”

By integrating the software with the EMCB, EPRI and Virtual Peaker have collaborated on a complete system that can be deployed for various applications. The system can help utilities aggregate devices for demand response and other utility- and customer-benefiting applications, potentially leading to a paradigm shift in utility load management. Historically, electric meters have measured a building’s aggregate energy consumption for billing purposes, and utilities have been unable to gather the detailed, real-time, appliance-level data needed to respond to changes in energy use.

Consider the possibilities for EV charging at a group of houses serviced by a transformer. If EMCBs are deployed at all the houses with an EV and Virtual Peaker’s software is integrated into the utility’s grid operations, the utility could monitor the total load on the transformer from all the EV chargers. An additional monitoring device would be installed on the transformer’s output side and integrated with the software. When the total load on the transformer is nearing the point of overload, the utility can send a signal via the software to the chargers to reduce charging from full capacity. Later, the software would recognize when one or more of the EVs has finished charging and would automatically send a command to the other vehicles to resume charging at 100%.

“With this approach, there’s never any worry about the transformer overloading,” said Reddoch.


Testing in the Lab and the Field

In an initial round of lab tests and field deployments completed in 2018, EPRI worked with 12 utilities to test whether the EMCB worked effectively to monitor and control one load at a time. In total, nearly 300 EMCBs were tested at 80 sites, monitoring and controlling loads such as HVAC equipment, water heaters, pool pumps, and EV charging systems. The testing demonstrated that the standard EMCB performed well, while the EV version needed additional development.

EPRI is now working with 12 utilities (some of which participated in the first pilot project) to examine the performance of the software-integrated EMCB system as it simultaneously monitors and controls a large number of loads.

“We’re progressing from testing the EMCB in isolation to testing it as part of an integrated software system that aggregates a collection of devices to achieve specific objectives,” said Reddoch. “This is where we can look at utility applications such as demand response, managed EV charging, and improved power quality. We can also quantify the benefits to customers, such as financial savings from reduced energy use—particularly during times of expensive peak demand.”

EPRI expects to test the EMCB system for these applications:

  • Controlling EV charging to avoid transformer overload
  • Controlling and scheduling the use of electric water heaters, pool pumps, and other appliances
  • Monitoring and optimizing the performance of residential solar systems
  • Monitoring and reporting on house voltage levels

“The big step forward in this next phase is learning how to use the Virtual Peaker software along with the EMCB device on a larger scale to meet utility priorities,” said Reddoch. 


This article appreared in the September issue of EPRI's Efficient Electrification newsletter. To sign up to receive future issues, visit:

Founded in 1972, EPRI is the world's preeminent independent, non-profit energy research and development organization, with offices around the world.
Matt Chester's picture
Matt Chester on Oct 1, 2020

But what happens when a few of the residential customers served by a transformer purchase an EV and then connect an EV charger?

“The load pattern changes and can exceed the capacity of the transformer, causing it to potentially overload,” said EPRI Principal Technical Executive Tom Reddoch.

These customer purchases pose a potential dilemma for utilities. 

I'm curious when this problem gets diagnosed as well-- is it simply a matter of the utility looking at load patterns and recognizing the increase in load? I know many utilities have programs for EV drivers (whether rebates for chargers, TOU rates, or otherwise) that help to pinpoint exactly when an EV is purchased, but not all do-- is the load profile immediately obvious to the utility? What about if a car is temporary (a rental, a guest visiting, etc.)-- will utilities know when to act based on those questions?

Thomas Reddoch's picture
Thank Thomas for the Post!
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