Implement a solar power monitor

[Naervern]

This will require some electronics calculations/design and can be left for later.

• Must be tuned to the specific device/PV cell models used...

• • Have a function which will monitor the level and estimate the current able to be supplied to the board, so it can turn the WiFi functions on (basically taking it out of Power Saving mode)
• • The current required for the system should be around 200-250mA at 3.3V. It's very important that the current drain from the supercapacitor is taken into account and thus it might be a good idea to implement it also with a current limiting solution for the supercapacitor, which ideally would be smart enough to balance the urgent need to charge the supercap, such as when its voltage level is below 2, for example, in which case it would maintain the ESP32-S2 in a power saving mode to prevent an unexpected interrupt, but otherwise would allow the MCU to draw the 200-250mA required for its full functionality and keep the surplus available for charging the supercap.

[Naervern]

• Presently, the photovoltaic module recommended is specified at 6V and 660mA, though how that behaves in a field test is yet to be seen.