I have found an easier way involving the Arduino MKR GSM 1400 and the new Arduino cloud service based off AWS.
- https://store.arduino.cc/usa/sim-bundle
- https://www.arduino.cc/en/Guide/MKRGSM1400
- https://forum.arduino.cc/index.php?topic=546250.0
- https://www.digikey.com.au/en/maker/blogs/2018/increasing-battery-life-by-40-times-for-a-dyi-arduino-based-sea-level-indicator
- https://create.arduino.cc/projecthub/Arduino_Genuino/securely-connecting-a-mkr-gsm-1400-to-google-cloud-iot-core-b8b628
You need to copy the solar library mpptChg into the arduino library folder for the solar charger.