Just out of curiosity, have you tried running Tasmota on the ESP32 to read the RS232 data? #14
Description
Tasmota IoT firmware should have everything needed to read the data being sent from the Renogy charger's RS232 port, as well as publish it to an MQTT broker.... provided you still use a data level shifter like the MAX3232 between the Renogy charger and the ESP32.
Was just curious if you had even tried Tasmota on the ESP32 before writing your own code?
Just curious because I am running some ESP32-CAM modules off a solar panel/battery and would like to pipe the solar charger's RS232 data into the ESP32-CAM... My ESP-CAMs are all running Tasmota.