This was my first project where I attempted to weld Li-ion batteries into a pack and tried out the Chinese spot welder.

It was built around the CN3722 MPPT board to which the solar panel was connected through the INA219 current sensor. The second sensor is connected between the battery and the remaining system to monitor the usage of the power pack energy. 

1.3" OLED display is used to show the required stats calculated by Raspberry Pi Pico. It communicates with display and sensors through a single I2C bus.

ESP32 dev board is running WLED to later control the bulb light string I am currently working on. Both boards are powered by a step-down converter set to 5V. 

The logic level shifter is used to convert the data signals of ESP32 from 3.3v to 5V to communicate with the bulb string. 

In future, I plan to add a sealed XC60 connector to the box to have easy access to battery energy to power other devices or quickly recharge it during cloudy days and high energy demand.

Solar Panel is facing North which is not optimal. At the time of testing it in the Autumn max power output was between 2-9 W which is only sufficient to power the electronics without the lights. I will be upgrading the panel to something around 100W so the mean power output would be sufficient to recharge the batteries during the day.