The electronics part of the solar tracker is quite simple as we reuse existing components which are mostly only integrated all together on a custom PCB.

Here is the schematics : 

The heart of the system is the Lolin32 ESP32 breadboard.

It is driving two steppers motors via two easydrivers boards. These drivers accept classical Step and Dir signals.

They can be switched into "sleep" mode preventing to draw too much current when the motion is finished. Note that in Sleep mode, the motors will loose their torque and may rotate freely.

Thanks to the "wormgear" design of the mechanical parts, the axis will not move if a force is applied on the panel even when the motors are off.

The board is powered either directly from the solar panel or via an external battery (which will be charged by the MPPT controller).

Nevertheless it may occur that the voltage at the input of the motors is not enough to perform a strong motion. This is the reason why this voltage is measured via the voltage divider R1/R2 and the ADC input of the ESP32 (VP pin).

Note as well that the lolin32 is equiped with a lipo charging circuit. This is why I have added a single cell 18650 li-ion to the board. This will allow to power only the MCU if the 16V signal is weak or not present. Doing this allows to preserve the software side of the system and thus to recover from cloudy situations !

This schematics has been translated into a single sided PCB

The PCB itself was etched with my "toner transfer" method explained on my web site.

Refer to the Gerber files log if you want to manufacture your pcb.