I'm not using load balancing, but I can tell my charger to only use excess power to charge (solar production over house demand). The solar system controller is running the charger. I leave the car on the max charge percent desired. I'm not sure I understand why the car would be controlling your balancing rather that the charger or solar system controller?

 

It's because the current draw is set by the car. The only thing the EVSE does is tell the car how much power is available. If it didn't do that, the car would always draw the maximum current the OBC (or ICCU) is capable of handling.

 

The EVSE needs a dynamic charging current profile, so the car'll adapt to whatever the EVSE sets.
EVSE power should stay on, even if it's telling the car 0A is available.
Make sure your integration doesn't totally cut the power.

 

Could be it, because when I tell the charger to disconnect and connect again (via the app, not physically unplugging) then the car resumes charging.

 

No. Orbis Viaris.
In the meantime I have found that it's possibly the EVSE. It should be configured with a parameter that can only be set by their support department to re-initiate charging when power becomes available again. I will contact them and see what happens.