There have been several exciting moves recently to use EV batteries to power more than just the vehicle. This is called bi-directional power flow since the power flows not only into the battery to power the car but also out of the battery to provide power to things like buildings or the electric grid. To help you keep track, here’s a roundup of some of those developments.

Pacific Gas and Electric (PG&E) is involved in two pilots to test out vehicle-to-building capabilities. It makes a lot of sense that they’d lead the charge considering fully one fifth of all EVs in the country are in the utility’s service territory in Northern and Central California.

One pilot is with Ford and the other with General Motors (GM). The Ford pilot will only work with the F-150 Lightning and the first installations will begin in Spring 2022. As part of the initiative, Sunrun will collaborate with Ford to install the necessary equipment to support the bi-directional charging including adding solar capacity. In theory, Ford says that the batteries could provide power to a home for three days. The GM/PG&E initiative will also focus on home back up power. Both initiatives are scant on details though the Ford initiative released a short video in February 2022 in which they explain how their proposal would work.

These initiatives are both Vehicle-to-Building (“V2B”), which helps to power a single site. This is different from Vehicle-to-Grid (“V2G”), which enables electric vehicles to provide power back to the grid. School bus pilots are popular for testing V2G potential with buses – particularly school buses – given the amount of time the buses are idle during the day.

It is, of course, not without challenges. Jennifer Hiller in the Wall Street Journal breaks down some of the key potential issues to come with V2G:

  • Need for more expensive technology and chargers – particularly as the chargers are more expensive than conventional chargers. EVs themselves are also still out of reach for many families, creating the risk that low-income families could be locked out of the benefits of these types of V2B and V2G.

  • Unknown impact on batteries including the potential that batteries may degrade faster due to an increase in charging cycles.

  • Creating incentives for owners to link up to the grid. Given the costs, the case for drivers to participate needs to be made – particularly if there are grid benefits that do not necessarily accrue to the drivers themselves.

The upsides though are potentially important. Given the impact climate change is having on weather patterns and the aging grid, battery backup could be crucial to prevent blackouts. Utilities already order “rolling blackouts” in times of severe weather or wildfire risk.

These V2B and V2G pilots will take time to roll out – the GM pilot for instance is still in the lab trialing options. However, if successful, these interventions could help support the grid and households through a changing climate.

Even without bi-directional power flow, EV batteries can provide substantial value to the electric grid simply by being flexible in when they charge, a practice sometimes referred to as V1G. Specifically, charging when electricity demand is low is extremely beneficial to the electric grid and does not require highly advanced technology. EVs also have the potential to provide demand response services to the grid by increasing or decreasing charging activity in response to the electric grid’s need, again without any need for bi-directional power flow. The Department of Energy explains how this could work: “sensors can perceive peak load problems and utilize automatic switching to divert or reduce power in strategic places, removing the chance of overload and the resulting power failure.”

At this stage, a lot of these developments remain in pilot form. So we wait and see…

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About the author: Tom Taylor