Often there’s an operational preference for charging EV fleets to full as soon as they return to the depot at the end of a shift. This post explores whether that approach is it the best way to do it.

A couple of weeks ago I posted some analysis looking at how much battery storage I would need to add to my existing solar system at home to be fully self-sufficient & 100% carbon free with respect to my electricity consumption.
The post generated a bit of interest & some questions around the impact that electric vehicles, in particular EVs with bi-directional charging, might have on the challenge. So it was back to the Gridcognition software to run some more simulations.
This time around I’ve added an EV with V2H (vehicle-to-home) capability to the mix to see how that changes the picture. Does the EV provide sufficient storage capability courtesy of its own very sizeable battery such that stationary storage isn’t required? Or does it add a heap of additional energy requirement & make the 100% carbon free goal even harder? Well, both is the answer.
First, some modelling assumptions:
The V2H feature will draw energy from the battery to offset my grid-supplied energy to the house whilst still meeting the requirements for driving. There are a few occasions where it sails close to the wind. I could maybe run a more conservative optimisation that preserves a higher minimum EV battery SoC
And to the results:
Now for the not-so-good news: I’m no longer able to go 100% grid & carbon free.
The additional energy requirement shifts the limiting factor from being the amount of storage to the amount of solar generation, particularly through the winter months of Jun, Jul & Aug where I simply don’t have enough solar yield to cover the needs of the house & EV.
Often there’s an operational preference for charging EV fleets to full as soon as they return to the depot at the end of a shift. This post explores whether that approach is it the best way to do it.
Octopus Energy in the UK recently announced a new tariff that offers free EV charging to their customers in exchange for the EV owner allowing Octopus to optimise the charging and discharge behaviour of the vehicle.