Standards for unlocking V2G – pv magazine India

Excerpt from pv magazine 02/2022

Electric vehicles (EVs) offer a glimpse of a variety of next-generation technologies, such as over-the-air updates, driver assistance, automated parallel parking, and central entertainment interfaces that can also serve as video game consoles. And while these innovations represent a new era for the automotive industry, electric vehicles’ greatest contribution to the energy transition may not be what they can do for the driver, but what they can do for the electrical network.

The potential for vehicle-to-grid (V2G) applications for electric vehicles is immense. While residential and utility batteries will play an important role in future energy systems, many experts predict that, if implemented effectively, electric vehicles as grid assets could operate on a scale that eclipses the current and forecast stationary energy storage market.

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Unlocking the services electric vehicles can provide requires bi-directional charging, a system that allows grid and distributed energy resources like residential solar power plus storage to recharge the car and return stored energy from the car to the grid if needed.

V2G technology

Although two-way charging technology already exists, it does so in three forms and, as the Interstate Renewable Energy Council (IREC) explores in its new report; “Leading the way, vehicle-to-grid standards for electric vehicles.” The authors review the state of V2G standards and identify gaps that need to be filled to unlock the full capabilities of V2G-enabled equipment.

To understand the potential and specific standardization needs in the V2G space, we must first understand the three inverter configurations currently possible with electric vehicles and their smart bi-directional chargers.

V2G-DC: In this direct current (DC) configuration, the power conversion and intelligent functions are housed in the electric vehicle power equipment (EVSE). The EVSE essentially functions as a stationary smart inverter, providing grid support benefits and communication functions to asset operators, in addition to converting energy.

V2G-AC: In this alternating current (AC) configuration, the script is reversed and the EV contains the power conversion and smart functions. Instead of the charger, the EV acts as a smart mobile inverter.

V2G-Split Inverter: In this configuration, the power conversion is located in the EV and the smart functions are housed in the EVSE, so neither the EV nor the EVSE on its own looks like a smart inverter . The report predicts that this setup will have the least application and traction going forward, so its implementation will be less focused than the previous pair.

Applicable standards

Each inverter configuration will require its own specific standards to cover its applicable functions and safe operations, such as interconnection, EVSE safety, vehicle functionality and communications.

In this space, interconnection issues fall under the IEEE 1547 series of standards and documents; EVSE safety and functionality are covered by UL standards, specifically UL 1741; EV standards and vehicle functions are handled by SAE; and testing may be performed by third parties or manufacturers. Communications is the area with the least existing standards, which means that work needs to be done to develop them.

The report authors recommend that in V2G-DC scenarios, EVSEs should be UL 1741 certified to ensure grid compliance. In V2G-AC scenarios, the authors recommend that EVSE and EVs be certified to UL 1741 SC, which is contained in SAE J3072.

UL 1741 is widely used for grid interconnection, providing guidance for evaluating inverters with specific grid compliance requirements, and has long been the standard for inverter certification. For V2G-DC, the EVSE can be considered as a stationary inverter, which means that interconnection requirements and grid integration compliance can be met through UL 1741 certification.

The same is not true for V2G-AC, because the inverter is in the EV and is not stationary. UL 1741 SC was developed to address this issue and has been adopted into SAE J3072. This standard establishes many of the same function requirements of the grid support inverter system, considering integration into an EV and connection to a power source through the EVSE. The standard also covers some aspects of hardware communication.

In short, the authors recommend that the EV be SAE J3072 certified and that the EVSE be listed to UL 1741 SC, which is contained in SAE J3072.

While these requirements may seem like overly technical jargon, establishing manufacturing, safety and operating standards is essential for any industry to evolve and reach its full potential. If every EV configuration operates in a predictable and standardized manner, it becomes enormously easier for operators of large-scale assets, such as utilities, to leverage the grid-supporting capabilities of this technology.

Making it easier for utilities to exploit the benefits of V2G will introduce the same utilities to the value of these assets, which means that steps will be taken to increase their adoption, through means such as rebates, incentive programs to landfill and extensive networks of public charging infrastructure. .

By Tim Sylvia, Editor, pv magazine USA

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