SAE adopts new standards for Vehicle-to-Grid

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There is a wonderful fantasy that the batteries in all the world’s electric cars could act as a giant, distributed virtual power plant that would store electricity from renewable energy sources when it is abundant and feed it back into the grid when demand exceeds the offer. . The batteries can also perform grid stabilization tasks. Thanks to V2G, short for vehicle-to-grid, utilities could save a lot of money by not having to buy their own grid-level storage batteries and pay electric vehicle owners for the privilege of using their batteries instead.

This dream is certainly attractive, but for it to become reality, many things have to happen at the same time. Professor Willett Kempton of the University of Delaware and his team of EV researchers first started using electric vehicles as grid batteries in 2007. Their first experiment of its kind has since been replicated in V2G projects around the world.

Kempton knows there are technology and policy gaps that prevent V2G from being widely adopted. That’s why he’s spent years working on a technology standard that could make V2G a realistic option for automakers, utilities and drivers alike. The standard is called SAE J3068. In January, SAE International formally adopted major new V2G capabilities, which Kempton calls a “practical, low-cost and implementable” way to turn any electric car into a roaming grid battery.

Why V2G standards are important

The big challenge, says Kempton Canarian media, provides utilities with all the data points they need to feel comfortable receiving power from electric vehicles. “If something is pushing power onto the grid, they want to know what that is,” Kempton said. “They don’t want to say, ‘We’re 95 percent sure which car it is.'”

Today, the charging technologies used in electric vehicles and charging stations are simply not set up to provide and manage that information, Kempton said. V2G is particularly complicated when it is the EV itself, rather than the charging station it is connected to, that needs to communicate with the utility. Level 1 and Level 2 chargers that operate on AC power are not equipped to send utilities the data needed to run V2G.

DC fast charging systems, on the other hand, contain inverters that convert AC mains power into DC power. These inverters manage the interaction of the electricity grid with the charger and the vehicle. But when charging at Level 1 and Level 2, the inverter is in your car, Kempton says. That makes any V2G-capable EV ‘a roaming inverter’, complicating matters for utilities. Now they have to certify an inverter that moves from place to place, instead of an inverter that is permanently connected to the same point of the grid.

Most EV drivers will use DC fast chargers to quickly charge and go, making it unlikely that their car will be available for V2G charging. AC charging, which takes place at home, at work, in shopping centers and other places where people leave their cars plugged in for hours, is a much more suitable setting for V2G for the mass market.

The SAE J1772 technology standard used for Level 1 and Level 2 AC charging is simply not capable of telling utilities everything they need to know. It “can say three or four things,” including whether it’s “connected to a charging station” and whether it’s “ready to charge,” Kempton says. It can also limit how much power an EV draws from the charging station. “That’s the entire repertoire of signals. That’s great if you want to plug in and charge, but not for much else.”

EVs that adopt the new standards will be able to manage “approximately 200 signals.” Furthermore, instead of using the simple analog communication system used in the previous iteration, the new standard uses technology that uses digital communication that can be transmitted via an existing wire in the charging cord itself or via wireless signals, making it much is more convenient. useful for communicating all kinds of things that most modern chargers can’t do.

V2G for level 1 and level 2 charging

For example, EVs using the old standard cannot send the various diagnostic codes and error signals that charging stations rely on to troubleshoot charging issues that can cause charging errors – a gap that is partially responsible for the problematic performance of many public EV chargers today.

Last year, SAE adopted a new update to the standard, J3068/1, which includes diagnostic and identification capabilities that EV drivers, automakers and charging station operators can leverage to better troubleshoot charging issues. It can also identify the car or account at the charging station, allowing payment without always having to use a credit card.

But what really excites Kempton is another SAE standard – J3068/2 – adopted last month that enables V2G capabilities for Level 1 and Level 2 charging. J3068/2 makes it possible to provide ‘electrical certification’ of individual vehicles by recognizing each EV through a unique digital identifier that utilities can reference to check whether they are authorized to supply power to the grid.

The same certification system also allows the utility to communicate ‘grid codes’ to EVs to stop discharging power if, for example, local grid circuits are overloaded, or to request power be supplied to limit disruptions to the grid. Finally, utilities can pay EV owners for voluntarily making their battery capacity available through a V2G system.

“In the case of DC [chargers]your inverter is stuck to the ground,” says Hamza Lemsaddek, vice president of technology at Nuvve, a V2G company that grew out of Kempton’s work at the University of Delaware. Nuvve coordinates profitable V2G projects in several European countries and Japan, as well as in Delaware and California, all of which use charging stations as control centers rather than electric vehicles themselves. “If you move to AC V2G, you have a roaming inverter and you need to make sure that wherever it connects, it has the correct settings as required by the local utility to inject power,” he said.

DC vs. AC

DC fast chargers use a standard called ISO 15118-20 to manage communications and operations between vehicles and the power grid. That standard is “great for DC V2G, but lacks some important signals and functionality for AC V2G,” he said. Utility pilot programs have focused on vehicle-to-home applications, which avoid the complications of returning energy stored in EVs to the grid, or they rely on less suitable standards and one-off technology solutions to test true V2G.

Kempton says he hopes automakers will soon build these new capabilities into their electric vehicles and that utilities will invest in the communications and control systems needed to work with them. If the technology is successful, it could help millions of EV owners use their batteries to make extra money and provide a significant boost to an increasingly stressed electricity grid.

As a first step, his team at the University of Delaware’s Science, Technology and Advanced Research Campus plans to launch a pilot project next month with Delaware-based utility Delmarva Power, one of six regulated utilities owned by the Chicago-based established Exelon. That pilot will test the newly standardized capabilities on a handful of commercial vehicles.

A 2021 study by Professor Brian Tarroja of the University of California – Irvine and Professor Eric Hittinger of the Rochester Institute of Technology found that V2G could make a big difference to California’s power grid. They calculated that the combined value of the energy storage capacity of V2G EVs in California is “approximately an order of magnitude greater than that for smart charging.”

NACS is simpler and cheaper

NACS standard
Image credit: Charged Electric Vehicles

Tesla’s North American Charging System (NACS) standard was certified by SAE two months ago for use by other charging manufacturers. That standard, known as J3400, supports a different communications technology that is easier and cheaper to implement than CCS technology and can be easily adapted to work with J3068/2. That “opens the door for mass adoption of that technology standard,” Lemsaddek said.

EV charger manufacturers are also gearing up to enable AC V2G capabilities in their chargers, says Eduard Castañeda, Chief Innovation Officer at Spain-based charger manufacturer Wallbox. “We expect this standard to accelerate bi-directional AC charging in the US and likely enable it even before Europe,” which is generally more advanced than the US in EV charging.

Kempton emphasized the importance of aligning utilities and automakers on V2G. “There are some that are significant [automakers] plans to put J3068 technology and sensing in future EV models, he said. ​“That’s an implementation decision that requires forward-looking engineering,” but comes at very little cost in exchange for much greater AC charging functionality and reliability.

Utilities also need to establish the interconnection processes for V2G-enabled EVs and payment programs that make it worthwhile for EV owners to sign up, Kempton said. At that point, the path on which his two decades of V2G work will come to fruition is relatively clear, he added: “You just need to have enough electric cars to make it happen.”


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