My solar/battery system is limited to 5kW so if I want to suck up some excess solar, I use the 3 pin cable. I normally charge to 80% and to harvest the excess, I have to set the car target charge to 100% otherwise it stops at 80%. It doesn't automatically change.
At night my batteries are set to forced charge so all the night time car charging comes from the main electricity supply which can charge at 7kW. Day time it upsets my solar battery system causing it to switch off and on constantly hence using the granny charger to keep below 5kW. There may be a problem with it but for now I can work round it. Not much sun around att.