What's not to love about vehicle-to-grid technology that leverages idle EVs to serve as mobile batteries, returning electricity to the grid?

Did you know that many vehicles are parked up to 90 percent of their useful life, including Electric Vehicles (EVs)? To date, "smart charging” has helped manage the one-way flow of energy from the grid to EVs during peak periods. But emerging vehicle-to-grid technology allows the energy to flow to and from parked and plugged-in EVs. This turns idle cars into mobile batteries that can return electricity to the grid or power buildings and other loads when they are not in use.

Understanding the potential

While still in the early stages of development, vehicle-to-grid technology offers a way to pull small amounts of energy from a plugged-in car when it is not in use, yet still ensure the EV has enough energy to be driven when needed. This innovation holds promise for customers and the grid. For example, vehicle-to-grid technology can reduce customer demand charges and provide greater grid balance during peak use hours. It can also enable vehicle batteries to serve as emergency power sources.

“We’re excited to learn how we can utilize vehicle-to-grid technology to reduce grid stress, empower customers, and increase renewable energy use,” said Jaron Weston, Clean Transportation policy manager at SDG&E.

Overcoming the challenges 

But the technology is not without its growing pains as it matures, including overcoming current market challenges and regulatory barriers to interconnection. At the moment, only certain EVs and EV charging stations are capable of two-way energy flow, and even fewer are compliant with CPUC rules around interconnection.

Next steps for Vehicle-to-Grid technology

We are planning a five-year vehicle-to-grid pilot program at the Cajon Valley Union School District. The program will connect six electric school buses to 60kW bi-directional DC fast chargers. The buses will discharge excess energy to the grid during peak demand hours, with the aim of reducing grid impacts and demand costs for the school.

Set to launch in Q4 2021, this pilot is the first-of-its-kind to test advance use cases of vehicle-to-grid technology and the first to receive interconnection approval with a key UL certification. If successful, the program can pave the way for future projects, including internal opportunities to test vehicle-to-grid technology with our truck fleet, which is on track to achieve zero-emission status by 2040.