Specify type of charge in API

I have created an automation in Home Assistant which handles charging of my M3 on excess solar. I'm using the TeslaFi API for both monitoring and control (turn on/off charging and set charge current). It would be very helpful if I could specify in the API an argument which records the charge type as solar (free) rather that it being picked up as a standard Home charge. Just being able to say "start charging as Solar" in the API call would be most useful.

Thank you