It’s an exciting week for grid resiliency-lovers in California, as Governor Gavin Newsom followed up his earlier smart grid law and signed another law this week which may require bidirectional charging on EVs in the future – though the law has no hard timeline attached, so it may be a while before we see this happen.

Bidirectional charging refers to the capability of electric vehicles to not just take electricity from the grid to charge, but to output electricity in various forms, whether this be vehicle-to-load (plugging in devices, like the 1.8kW capability on the Kia Niro EV), vehicle-to-home (like Ford’s “Intelligent Backup Power” system), or vehicle-to-grid (like the Nissan Leaf is capable of).

While these applications may seem like a party trick, widespread use of bidirectional charging could lead to huge benefits for efficiency, grid resiliency, and enable much greater penetration of renewable electricity generation.

Most electric grids don’t really have trouble meeting the regular everyday needs of electricity consumers, it’s when big spikes happen that things get difficult. Either on a hot day when everyone is using air conditioning, or a day when electricity generation is curtailed for some reason or another, that’s when things get difficult.

And as climate change makes temperatures hotter, California’s grid is often overtaxed on the hottest summer days, which are becoming more numerous. Even worse, methane-burning fossil gas peaker plants are the highest-polluting form of electricity California consumes, and these are currently used at peak times in order to deal with high demand.

One solution to this problem is adding energy storage to the grid which can be dispatched when needed, and which can fill up when the grid is oversupplying electricity. This helps to balance out supply and demand of electricity and make everything a little more predictable.

This is why there has been a push for grid-based storage like Tesla megapacks, which represent a large source of rapidly-dispatchable energy storage.

But there’s another source of grid-connected batteries out there which was right under our nose the whole time: electric cars.

EVs, which are mostly connected to the internet anyway, could be used as a distributed energy storage device, and even called upon to help provide electricity when the grid needs it. We already see this happening with Virtual Power Plants based on stationary storage, but if cars had V2G, theoretically cars could contribute in a similar way – both saving the grid, and perhaps making their owners some money along the way via arbitrage (buying electricity when its cheap and selling it when its expensive).

The problem is, not many automakers have included V2G capabilities in their cars, and in the cars that do have it, not many manufacturers have made V2G-capable equipment, and the ones who have built it haven’t seen that many customers who are interested in spending the extra money to upgrade their electrical systems with V2G-capable equipment.

So there needs to be something to jumpstart all of that, and California thinks it might just have the thing.

New CA law might require bidirectional charging… eventually.

The idea started in 2023 when state Senator Nancy Skinner introduced a bill which would require EVs to have bidirectional charging by 2027.

As this bill made its way through the legislative process, it got watered down from that ambitious timeline. So the current form of the bill, which is now called SB 59, took away that timeline and instead gave the California Energy Commission (CEC) the go-ahead to issue a requirement whenever they see it fit.

The bill directs the CEC, the California Air Resources Board, and the California Public Utilities Commission to examine the use cases of bidirectional charging and give them the power to require specific weight classes of EVs to be bidirectional-capable if a compelling use case exists.

The state already estimates that integrating EVs into the grid could save $1 billion in costs annually, so there’s definitely a use case there, but the question is the cost and immediacy of building those vehicles into the grid.

The reason this can’t be done immediately is that cars take time to design, and while adding bidirectional charging to an EV isn’t the most difficult process, it also only really becomes useful with a whole ecosystem of services around the vehicle.

Even Tesla, which for years has touted itself a tech/energy company and sold powerwalls, inverters, solar panels and so on, is still only gradually trickling its bidirectional Powershare feature out onto its vehicles.

And that ecosystem has been a bit of a hard sell so far. It’s all well and good to tell someone they can make $500/year by selling energy to the grid, but then you have to convince them to buy a more expensive charging unit and keep their car plugged in all the time, with someone else managing its energy storage. Some consumers might push back against that, so part of CEC’s job is to wait to pull the trigger until it becomes apparent that people are actually interested in the end-user use case for V2G – otherwise, no sense in requiring a feature that nobody is going to use.

Electrek’s Take

Given all of these influences, we wouldn’t expect CA to require bidirectional charging any time soon. But it still gives the state a powerful trigger to pull if other efforts, like the recently-signed smart grid law, turn out not to be enough as California works to, grow, clean up, and make its grid more affordable all at the same time.

But having the force of law behind it could turn V2G into less of a parlor trick and more into something that actually makes a difference the way us EV nerds have been dreaming of for decades now (true story: Electrek once turned down Margot Robbie for an interview and instead talked to some engineers about V2G for an hour).

So, telling manufacturers that California may start mandating bidirectional charging soon means that those manufacturers will perhaps start taking V2G more seriously, particularly given the size and influence of CA’s car market. Even if the CEC doesn’t make it a requirement, the threat of it eventually becoming one means that EV-makers will probably start getting ready for it regardless.

There’s no real point to a single person discharging their car into the grid, but when millions of cars are involved, you could work to flatten out the famous “duck curve,” which describes the imbalance between electricity supply and demand. We hear a lot about “intermittency” as the problem with wind and solar, and grid storage as the solution to that, so being able to immediately switch on gigawatt-hours worth of installed storage capacity would certainly help to solve that problem. And we hope this law helps us get just a little closer to that potential future.

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