Vehicle-to-grid (V2G) technology is touted as the next frontier for electric vehicles (EV) but turning cars into an extension of the power grid creates new engineering challenges across the energy ecosystem. Engineers from automotive original equipment manufacturers (OEM) and grid operators must overcome various implementation challenges to capitalize on V2G growth drivers. Breaking away from traditional test methods will play a pivotal role in bringing this transformative technology to market.

Recognizing the driving forces behind V2G

Achieving net zero emissions is at the core of government initiatives worldwide, with most countries aiming to reach this goal by 2050. To achieve this objective, the transportation and energy industries will need to overcome various business and technical challenges as they transition to EVs and renewable energy generation. With EV adoption increasing rapidly, these activities are already having a ripple effect throughout the power grid.

For example, EVs are expected to add significant load on the power grid, especially late in the day as owners plug them in to recharge. The International Energy Agency (IEA), a reference for insights into the energy sector, estimates that electricity demand from EVs will reach almost 2,200 TWh by 2035 taking into consideration the current policies and measures put in place by governments around the world. The demand could be 23% higher (2,700 TWh) if accounting for the ambitions and targets announced by these entities [1]. By comparison, the global cumulative electricity consumed by charging EVs only totaled 130 TWh in 2023.

Greater electricity consumption from EVs, combined with the variability of wind and solar—the world’s two fastest-growing sources of energy generation—and the surge in electricity consumption from compute-intensive data centers for AI creates a perfect storm for grid operators who face the challenge of balancing electricity supply with demand.  

V2G is emerging as the answer to this challenge and more. The technology provides grid operators with immense capacity of dispatchable energy resources to stabilize the grid. By turning EVs into intelligent, communication-capable mobile energy storage assets, aggregate pools of EVs can become virtual power plants (VPP) and export power back to the grid when it is most needed, helping to balance the supply and demand of electricity, regulate grid voltage and frequency, and increase the overall reliability and resiliency of energy infrastructure while also reducing electricity costs for consumers.

V2G can also provide a slew of additional cost-saving benefits to utilities such as enabling the deferral of expensive grid infrastructure upgrades otherwise required to meet their forecasted load growth. The technology also supports decarbonization initiatives by providing a robust storage medium for accommodating higher penetration of variable renewable energy generation.

Tapping into the energy stored in EV batteries when vehicles are connected to the grid but idle is a game changer for grid operators. The storage capacity of millions of EVs can provide the energy needed to balance electricity supply with demand and avoid dreaded power outages. A case study for the city of Munich in Germany found that V2G technology could provide 200 MW of power to the city in 2030, representing 20% of its peak load during the summer [2]. Such power levels could help the city reduce its use of non-renewable energy sources, generate infrastructure savings, and help it achieve its sustainability goals.

Utilities foresee the integration of renewable energy sources as a major benefit from the mass adoption of V2G. Overall, many industry players expect the adoption rate of V2G to grow in the future. Earlier this year, a poll of senior decision makers in the automotive and power industries revealed that they expect V2G adoption to reach 20% to 50% in the next decade, putting the onus on research and development now [3].

The future of V2G technology looks bright, but its seamless integration is crucial for fulfilling its potential. Transforming EVs into mobile distributed energy resources (DER) for the power grid requires extensive conformance testing of communications and power flow.

Understanding V2G implementation challenges

Strained power grids, financial incentives, and the mass adoption of EVs are the primary catalysts for V2G growth and implementation. Benefiting from government support, V2G is witnessing significant uptake in China, Europe, and the U.S.

Connecting V2G-enabled EVs to the power grid does increase complexity, though. EV and EV supply equipment (EVSE) engineers must ensure conformance to various cross-domain standards for charging, communication, and grid interconnection purposes.

Key V2G standards to know

The combination of a V2G-capable EV with a V2G-capable EVSE creates a DER. DERs must comply with multiple standards and undergo lengthy and expensive certification processes to be allowed to export power to the grid. The requirements span electrical/power transfer and communications with DER managing entities such as utilities, aggregators, and V2G charging network operators (CNO). Standards compliance is the most difficult technical challenge facing engineers working on V2G today as standards evolve rapidly and differ by region, country, and even state.

In North America, compliance with IEEE standards 1547.1-2020 and 1547-2018 is essential. Most U.S. states have adopted these standards or announced their intent to adopt them. These standards provide the technical requirements and conformance test procedures for equipment interconnecting DERs with the power grid and the specifications and testing requirements for interconnection and interoperability with the power grid.

IEEE standard 1547/1547.1 specifies additional standards that need to be implemented for compliance including communication protocols IEEE 2030.35, SunSpec Modbus, and IEEE 1815 (DNP3). The standard requires the implementation and testing of at least one of these protocols for interoperability. IEC 61850 and the Open Charge Point Protocol (OCPP) are other protocols under consideration.

In Europe, EN 50549 is the reference for national standards. EN 50549-1/-2 provides the technical requirements while EN 50549-10 covers the test requirements. This standard does not cover interoperability/communications test but specifies the protection functions and capabilities for DERs to operate with the grid.

Being familiar with OCPP is also important when working on EV charging stations and/or charging network management software. This standard is gaining momentum as a preferred medium of communication between CNOs and EVSE for charging infrastructure management. The most recent version of the standard does not support bidirectional charging, but the next one (OCPP 2.1) is expected to support it as well as harmonize with IEEE 1547 for V2G / EV-as-a-DER use cases. With CNOs playing the role of a DER aggregator, OCPP 2.1 can potentially serve as another method for ensuring efficient communications between charging stations from different vendors and grid management systems.

In addition, being knowledgeable about IEC 63110-1:2022 is helpful when working on V2G applications as this standard establishes a common communication framework for the EV ecosystem. Managing both EV and EVSE charging and discharging, it covers various aspects including energy transfer management, EVSE asset management, as well as payment and cybersecurity to ensure all systems involved in the V2G process can communicate effectively and securely.

For China, the China Compulsory Certificate (CCC) mark represents product compliance with standards. There are different standards for DERs, depending on the category. For example, GB/T 34708-2019 refers to photovoltaic grid-connected inverters while GB/T 36547-2018 and GB/T 36548-2018 cover electromechanical energy storage systems. These standards include sections on communications tests for interoperability purposes.

V2G test and certification procedures

In addition to various standards, multiple V2G architectures are possible depending on the location of the grid-connected inverter and its controller, either onboard the EV or EVSE. The V2G architecture then defines the applicable standards for certification [4].

The DC-V2G architecture (Figure 1) adopts a configuration with the smart inverter as well as the control and communications located in the EVSE. This configuration requires engineers to verify that the EVSE meets grid code requirements.

Figure 1 DC-V2G architecture adopts a configuration with the smart inverter as well as the control and communications located in the EVSE. In this architecture,  the EVSE must meet grid code requirements. Source: Keysight

This is in contrast with the AC-V2G architecture seen in Figure 2, where these components reside in the EV. As a result, engineers need to ensure that the EV meets grid code requirements for this architecture.

Figure 2 AC-V2G architecture where the smart inverter as well as the control and communications reside within the EV. In this case, the EV must meet grid code requirements. Source: Keysight

The split AC-V2G architecture in Figure 3 presents yet another configuration with the inverter in the EV and the control and communications in the EVSE. This hybrid approach requires evaluation of the paired system.

Figure 3 Split AC-V2G architecture with the smart inverter in the EV and the control/communications in the EVSE, requiring evaluation of the paired system to meet grid requirements. Source: Keysight

Overcoming V2G implementation challenges

Engineers can use traditional methods to test DERs using real EVs and charging stations, but this approach is cumbersome and time-consuming. Typically, it requires months of testing.

Emulation is an appealing alternative. These systems can mimic the communications and power flow of V2G-capable EV, EVSE and the grid, enabling engineers to test their EV or EVSE against various standards and verify communications and power transfer between the two much faster.

Using a DC power source with an emulator to function as an EV or EVSE, engineers can assess the charging and communications performance between their EV and any EVSE and vice versa. An AC emulator can replace the utility power grid, enabling them to test various interconnection standards.

The emulation method affords engineers the flexibility they need while enabling them to conduct the testing faster. With this approach, they can repeat and iterate tests more rapidly compared to using traditional methods.

A more sustainable future with V2G

V2G technology stands at the cusp of revolutionizing the automotive and energy industry by transforming EVs into dynamic energy storage solutions and presenting a promising avenue for their integration into the energy ecosystem.

The potential benefits for grid operators are immense, offering a means to stabilize the grid and increase its resilience. However, the path to widespread V2G implementation is not without challenges. The breadth of standards and the existence of multiple V2G architectures to cater to different use cases require considerable efforts from engineers to ensure standards compliance.

With the right investment in research, development and testing, V2G will play a pivotal role in achieving a sustainable, low-carbon future.

Jessy Cavazos is part of Keysight’s Industry Solutions Marketing team.

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References

1. Global EV Outlook 2024, International Energy Agency
2. Smoothing the Wave: EVs Enable Significant Peak Shaving, Siemens
3. Exploring the Future Vehicle-to-Grid (V2G) World: Driving Forces, Challenges, and Strategic Insights for Automotive and Energy Leaders, Reuters in partnership with Keysight Technologies
4. Electric Vehicles As Distributed Energy Resources eBook, Keysight Technologies

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