Sun Tracker
We set out to build a solar tracker.
The tracker uses two Nema 23 bipolar stepper motors to rotate 2 photovoltaic cells around the altitude and azimuth axes. We have three tracking algorithms to track the sun. The first moves the PV panel in little squares in spherical coordinates, finds the point on the square with the best voltage, and moves there, then starts over. The second moves in a little square, finds the voltage gradient, and uses that to decide where to move. The third uses the second strategy to find 5 or 6 good points spread 1hour apart, uses a multivariable, nonlinear, least-squares fit to find its latitude, the day of the year, the time of day, and then predicts where the sun will be next. It will use this equation for a few repositions, and then check to make sure it’s right using the second algorithm. In moving the PV panel, our stepper motors ramp up to speed in order to prevent overshoot and jerk/rattling.
Sun Tracker Working Video
We built this little prototype as part of an embedded systems class I was taking Fall of 2008. The green pcb board mounted on the plastic "table" was harvested from an old optical mouse.
