The longer it takes for V2G to become widespread, the more I think we're going about it all wrong. Take a tiny 400 volt stationary battery that's already grid-tied. Add a DC charge cable and 2 contactors to the battery box. Switch from stationary to vehicle battery whenever it plugs in. - ThreadSky

willparker.bsky.social • 1 day ago

The longer it takes for V2G to become widespread, the more I think we're going about it all wrong.

Take a tiny 400 volt stationary battery that's already grid-tied. Add a DC charge cable and 2 contactors to the battery box. Switch from stationary to vehicle battery whenever it plugs in.

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willparker.bsky.social•1 day ago

Most utilities already have programs for hybrid solar inverters with batteries. There's no need for utilities to treat EVs differently. There's no need to put the inverters and grid-tie smarts into the car. The UL EVPE standard has been out for years now. Just unlock the dang cars already.

willparker.bsky.social•1 day ago

Seems like the new NEMA standard is basically them explaining this point for inspectors & utilities.

It's great that V2G-AC is included in the standards and all, but I'd be willing to bet you'll never see such a creature in the wild - it's effectively just a red herring to confuse the AHJs.

mistermadge.bsky.social•1 day ago

SAE J3068/2 provides the technical spec for V2G-AC.

Would be enormously beneficial for workplace charging and resiliency, but it first needs much more EV market share.
https://cleantechnica.com/2024/02/22/sae-adopts-new-standards-for-vehicle-to-grid/

willparker.bsky.social•1 day ago

Good point. Even there, I'm still not convinced AC makes enough sense to justify all the extra design, equipment and regulatory confusion that goes with it.

There's not much cost delta between DC-EVPE and AC-EVPE units, and in a large install you also want charge load mgmt, adding complexity

willparker.bsky.social•1 day ago

Workplace V2G makes more sense for fleets than commuter cars - you need capacity/energy most when commuters are on the road or at home, implementing onboard grid-tie inverters is simpler if they're all ford transits or blue birds. But you would need to overbuild charge capacity to recharge faster.

willparker.bsky.social•1 day ago

If I was designing a workplace V2G scheme from scratch, it would use a multipoint V2G-DC scheme where each EVPE is DC-DC, which combine at a central inverter for AC conversion. UL1741 has a ton of control and relaying requirements, adding and verifying that in every vehicle is asking for trouble

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