What is Bidirectional Charging or “V2G" Technology?

What is “V2G" and how does it work? What is bidiÂrecÂtionÂal chargÂing? What cars enable bidiÂrecÂtionÂal charging?
"V2G" stands for “vehiÂcle-to-grid", a chargÂing techÂnolÂoÂgy that allows enerÂgy in an elecÂtric car batÂtery to be pushed back into the elecÂtriÂcal grid. It can also be referred to as bidiÂrecÂtionÂal chargÂing because of the two-way flow of elecÂtriÂcal enerÂgy. The idea is simÂiÂlar to smart chargÂing where chargÂing powÂer is increased or decreased as necÂesÂsary, but V2G goes one step furÂther and allows the charged powÂer to be pushed back to the powÂer grid to balÂance enerÂgy conÂsumpÂtion and proÂducÂtion variÂaÂtions when necessary.
When plugged into a V2G chargÂer, EV driÂvers can choose to either charge up their cars from the grid or sell back stored enerÂgy from their car to the grid. V2G chargÂing allows EV batÂterÂies to be used much more effiÂcientÂly than traÂdiÂtionÂal uniÂdiÂrecÂtionÂal chargÂing and is imporÂtant for fightÂing cliÂmate change and movÂing away from fosÂsil fuels. RenewÂable enerÂgy like wind and solar can’t be proÂduced on demand and needs to be either used immeÂdiÂateÂly when it becomes availÂable or stored someÂwhere for latÂer use. EV batÂterÂies proÂvide a perÂfect place to store this enerÂgy, and once stored, it can be pushed back into the grid durÂing peak demand times and to help avoid blackÂouts or powÂer surges withÂout the use of fosÂsil fuels.
The most imporÂtant aspect of V2G chargÂing is makÂing sure that the batÂtery is charged enough when the car needs to be driÂven, someÂthing easÂiÂly solved using phone apps that allow you to choose what charge you need at any givÂen time. That way, when the car is helpÂing balÂance the grid, it only uses some of the enerÂgy from the vehiÂcle and keeps the charge withÂin a set tolÂerÂance. Since cars are plugged in 90% of the time, it makes sense to use the batÂterÂies to balÂance the grid when they’re not in use.
The only vehiÂcles out right now that have V2G capaÂbilÂiÂties are the NisÂsan Leaf and the NisÂsan e‑NV200, but othÂer manÂuÂfacÂturÂers aren’t far behind. Ford has made vehiÂcle-to-home (V2H) capaÂbilÂiÂties for the F‑150 LightÂning elecÂtric pickÂup and may add V2G chargÂing in the future. VolkÂswaÂgen has announced that all their ID. brandÂed vehiÂcles will have V2G capaÂbilÂiÂties startÂing in 2022 and EV ConÂnect, leadÂing provider of EV chargÂing soluÂtions, is already runÂning triÂals on V2G techÂnolÂoÂgy in the U.S.

Sources:
https://www.virta.global/vehicle-to-grid-v2g
https://www.ovoenergy.com/guides/electric-cars/vehicle-to-grid-technology.html