How Vehicle-to-Grid Technology Helps Support the Power Grid

Key Points

• Vehicle-to-grid technology can allow participating electric vehicles to send stored electricity to the power grid.
• UL Solutions' new certification program helps manufacturers demonstrate the reliability and grid-support performance of bidirectional charging equipment for EVs.
• By supporting confidence in these emerging systems, the program can help increase the value of electric vehicles and advance a stronger, more resilient power grid.

With the right technology, electric vehicles can be useful even when they're parked. Vehicle-to-grid (V2G) technology can enable participating EVs to send electricity back to the power grid when demand is high and recharge when demand is lower.

A new program from UL Solutions supports the testing and certification of bidirectional electric vehicle supply equipment, which acts as a bridge between EVs and utilities by helping monitor and manage the flow of electricity.

The Q&A below explains how V2G technology works, why it matters and how certification can help build confidence in its safety, reliability and performance.

What is V2G technology?

Vehicle-to-grid (V2G) technology allows a participating electric vehicle to send electricity stored in its battery back to the power grid. Instead of electricity flowing only from the grid to the vehicle, V2G systems enable electricity to flow in both directions.

This means an EV could charge when electricity demand is lower and return some of its stored energy when demand rises or the grid needs additional support.

How could parked EVs be useful to the grid?

According to an Electric Power Research Institute study, approximately 90% of electric vehicles are parked at any given time under typical driving patterns. That creates an opportunity for participating vehicles to function as a distributed source of stored electricity while they are not being driven.

This flexibility could help reduce peak electricity demand, ease pressure on local infrastructure and allow available power to be used more effectively. V2G technology could become increasingly valuable as utilities face growing electricity demands from commercial buildings, data centers, manufacturing, transportation and other sectors.

What equipment makes this two-way flow of electricity possible?

Bidirectional EV supply equipment acts as a bridge between the vehicle and the utility, helping monitor and manage electricity as it flows to or from the vehicle.

The equipment must be used with a vehicle designed for bidirectional power flow. It must also support applicable utility requirements for safely connecting equipment to the electric grid.

What has UL Solutions launched?

UL Solutions has launched a testing and certification program for V2G technologies. The program addresses bidirectional EV supply equipment and helps manufacturers demonstrate the safety, reliability, grid interconnection and grid-support performance of their products.

The program enables products to be evaluated in accordance with UL 1741 Supplement SC, a supplement to UL 1741, the Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources. Additional certification pathways can use the UL 1741 multipiece distributed energy resource requirements together with UL 9741, the Standard for Electric Vehicle Power Export Equipment.

How does the certification program support manufacturers?

Through testing and certification, manufacturers can demonstrate that their bidirectional charging equipment meets applicable requirements for safety, reliability, grid interconnection and grid-support performance.

Products certified to UL 1741 Supplement SC can work with electric vehicles that use onboard bidirectional inverters designed and tested in accordance with the standard SAE J3072.

How could V2G technology benefit utilities and communities?

V2G technology could give utilities another way to manage periods of high electricity demand and improve grid resilience. EVs could provide stored electricity when additional grid support is needed and recharge during periods of lower demand.

At a broader level, these systems could help utilities integrate renewable energy, reduce peak demand and use existing grid infrastructure more effectively. They could also expand the value of EV batteries by allowing them to serve as a grid resource when the vehicles are parked.

Where are UL Solutions' V2G testing and certification services performed?

UL Solutions delivers these services at laboratories in Fremont, California, and Northbrook, Illinois.

Where can I learn more?

More details about UL Solutions' certification services are available in this Sept. 14 press release.

Additional information about the safety and performance of V2G technology is available on the Distributed Energy Resource Testing service pageat UL.com.