Hi, I am also experiencing problems and resetting the MESHTOWER device.
Tested two times with different temperatures (Street temperature -12 -16°C and House Attic house temperature +17°C) and with all the firmware’s presented
here
https://resource.heltec.cn/download/MeshSolar/firmware
- firmware-heltec-mesh-solar-2.7.14.e959000.uf2
- firmware-heltec-mesh-solar-2.7.15.567b8ea.uf2
- meshsolar_meshtastic_2.7.4.uf2
and on Github Meshtastic Firmware 2.7.17.9058cce Alpha
The operating time before crashing / freezing and resetting all settings is 10-15 hours in any use, I also tried with and without the connected solar panel from the kit.
I noticed a feature that after the MeshSolar - BMS freezes, it does not respond to commands on Param Sync https://resource.heltec.cn/utils/flash to connect, you need to flash* Meshsolar BMS Stock Firmware (meshsolar_bms_0.0.1.uf2), then configure from scratch as a new device 
Settings BMS Temp protection