I have another question for you or anyone else in the same situation:
On another forum, a discussion started about my decision to put my smart 11kW EV charger on the grid side (non-backup). Some people were saying I should put it on the backup side; otherwise, I wouldn’t be able to charge (including solar charging) if the grid goes down.
That only happens about 0.02% of the year, so I’m not really worried about that. On the other hand, putting it on the backup side would make my cable run from the car to the Victrons approximately 50 meters longer. I would also potentially use up 11kW of the 12kW maximum the system can deliver and could empty my ESS battery into the car in just two hours.
I know software controls can manage this, but my goal is to keep the house as reliable as possible, and I don’t mind the car being unable to (solar) charge during a rare blackout.
I built it to understand the system properly, not just plug and play. Played with BMS, protections, behavior under load, all of that. It was basically my test bench.
For the final installation I went with ready-made certified batteries, and the inspection was done without the DIY one. I didn’t want any discussion there, so I kept it clean from a compliance point of view.
I’ll disconnect the DIY battery and reuse it in off-grid projects later. There it makes more sense and no headaches with approvals.
On the EV charger, I would do exactly what you did.
Putting it on the backup side for a 0.02% scenario doesn’t make much sense, especially with +50m cable and a big load like 11 kW sitting on your ESS. That’s just asking for trouble if something is not perfectly controlled.
I also see the EV as a non-critical load. House stability comes first.
If later you want to optimize solar charging, you can still do that with control logic, you don’t need it physically on the backup side for that.
