Solar power for tank monitoring

One of our tanks is a little far away from a GPO for the tank monitor ( to be mains powered. I tried a commercial solution used to power wildlife cameras unsuccessfully but a little Arduino weather station power project did the trick.
This project was the basis of the power supply built to support the tank monitor. Two Jaycar modules were used:
  • Arduino Compatible Lithium Battery USB Charger Module CAT.NO: XC4502
  • Arduino Compatible 5V DC to DC Converter Module CAT.NO: XC4512
And a few Ebay sourced components:
  • 18560 lithium battery
  • 18560 lithium battery holder
  • 6V solar cell
The end result has been reliable for the last few weeks but the real test will be in winter with fewer hours to recharge the battery (which partially discharges over night) and run the depth sensor.