This project develops a photovoltaic (PV) solar tracking controller. Pictured above is the revision 2 prototype. PV solar trackers control the PV panel direction to keep the panel perpendicular to the Sun, maximizing the power output. The power output difference for a fully aligned panel is reported to be in a range of 15~40%, which would be substantial.

The goal is a self-orienting dual-axis, scheduled, Arduino-based solar tracker. I want to control PV panel orientation for both Elevation and Azimuth angles (dual-axis), based on the calculated solar position of a PV systems specific geographic location and time (scheduled).

Working under space, cost and time constraints, the prototype development is done on a small scale model. Eventually, I want to control and optimize the orientation of Mini-PV systems.

This is a interim revision to establish PCB design and manufacturing. The next version is revision 3, located here

The main controller board contains the 32bit Arduino MKRZero MCU, the LSM303 magnetometer sensor, DS3231 RTC clock module, and four 16pin GPIO expander circuits. A 128x64 OLED display shows operational data and status messages.

A 32-color LED display board connects to the controller board to develop the GPIO controller functions for the sun positioning display.

In the next revision, the 32 LED ring will form a ring that represents the horizon with north, sunrise and sunset indicators, and a green indicator to display the suns daily movement over time.

The solar position data gets calculated off-system in advance, and saved into a micro SD card. The pre-generated daily sun position files are then read by the Arduino MKR Zero microcontroller through the onboard card reader. The astronomical calculations of the suns position require sufficient CPU power, and are taxing on Microcontrollers.

At the moment I am using a sun position dataset that covers two years of operation, and uses approx. 20MB in size (46 MB with additional debug data). I wrote the “suncalc” tool to pre-calculate the data set files for a specific location, on a Linux PC.