Hello everyone,
my society created a project based on the heltec wifi lora v2, the goal is to acquire some sensor’s data then send it to our remote server via LoRa.
The software is based on paxcounter example, customized for the sensor we’re using. the board is designed for being powered in two different way, one with a battery pack charged by solar panel, one from the electrical line with an AC/DC converter.
The second case is working fine, the first one is giving us some trouble.
The big problem is that the board freeze, sometime after 20 minutes, sometime after 10 hours, but only when the solar panel is connected, if we simulate it with a bench power supply with costant voltage, no error occour in a week.
The solar panel (50W 18V 2.86A) is drived by a Epever Tracer2610BP, the output of the battery is 13,2V (14.2 max) is scaled to 8V for limiting the heat generated by the two LDO used for the conversion of the Vin (8V) in 5V and 3.3V, the former is used for the ESP32 and other sensor, the latter is used to power up some sensor.
Filters, big capacity on battery output for the noise reduction, nothing works, the system freeze after random time only in this scenario (solar panel + battery), others (banch power supply + battery, only battery, external power supply like a 12V - 1,25A or 5V 2A) all works fine for weeks.
Do you have any suggestion? external reset? more supply filter? i don’t know what to do next 
Ps: I have some issue on the I2C line too, sometime it result to be busy, but always recover, i made some test, the result is the same with 10K, 4.7K, and 2.2KOhm pullup resistance between SDA/SCL and 3.3V
Thank you for help