Responded to @py2toz:
@py2toz with a 6V panel you don’t need MPPT since it is so close to the voltage of the board.
I would connect it directly to Heltec’s 5V pins since the onboard TP4054 can handle 6.5V per datasheet.
Wrote about my experience here https://kaspars.net/blog/solar-lora-meshtastic