ALD910026 DUAL SUPERCAPACITOR AUTO BALANCING (SAB™) MOSFET ARRAY. TPS6120 Low Input Voltage Synchronous Boost Converter With 1.3-A Switches INA219 Zerø-Drift, Bidirectional Current/Power Monitor With I2C Interface. ADS1114IDGS Ultra-Small, Low-Power, I2C-Compatible, 860-SPS, 16-Bit ADCs With Internal Reference, Oscillator, and Programmable Comparator

J1 1 - GND 2 - VCC-Out 3 -  ADD SELECT 4 - SDA 5 - SCL/Analog output 6 - RDY 7 - Solar test control

J2/SOL1 Solar Panel input



A similar board was used with an ATMEGS328P and an LORA RFM95W communicated every 10 minutes to The Things Stack. Without sunlight it was able to communicate for 72 hrs. The power usage graph below sowing coms burst then deep sleep. In practice it has been working in my letterbox for the last 2 years without let-up.  ( see