Living Sustainably
in the shadow of climate change

March 2015
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A sun tracker for my 2 new panels
Filed under: General, Solar Power
Posted by: Guy @ 5:47 pm

When I first mounted 2 additional panels to the south wall of my workshop it was March and I mounted them at a steep angle.  Later in the season as the sun rose higher in the sky I extended the brackets to capture more energy in the summer months by tilting them further out from the wall.  I realized that an optimal solution would be to adjust them frequently to optimize performance.  So I decided to build my own tracking system that would adjust the tilt angle automatically.  I started by designing a sun sensor that uses two photocells inside a little green plastic dome:

A flat black piece of metal separates them and when the sun shadows one of the cells it sends a signal to the control box that I designed that moves the linear actuators that I purchased.  This image shows the control box mounted to the wall inside my window with the sensor mounted to the side of one of the panels so that it moves with the panel:

And here is a closer picture showing the control box that I built:

Here is my schematic if you are interested in making one for yourself.

I can set the slide switch to the left position which puts the system into automatic, or in the right (manual) position I can press the green button to tilt the panels out away from the wall, or the red button to tilt them back in.   This may come in handy in the winter when I need to shed snow off the solar panels, or “furl” them in the case of high winds. The stroke of the linear actuators can drive the panels from about 24° in winter 52° in summer.  This is the best range I could accomplish with the available actuator lengths (my winter solstice elevation is 22.4° and summer elevation is 67.18° here in Maine).  The actuators have built in switches that shut off the motors at their maximum extensions so they do not try to drive beyond their limits.  Since we are close to the summer solstice right now the actuators are fully extended, and over the next several months I will see the system adjust as the sun angle lowers.

3 Responses to “A sun tracker for my 2 new panels”

  1. rj Says:
    Pretty cool. Now you need an interface to an inexpensive wind speed indicator so that it can automatically retract when needed. It seems the system could be preprogrammed for position based on date and respond accordingly.
  2. Guy Says:
    I have a weather station, but the interface is beyond my skill level. Plus I’m not too worried about the wind issue as I over built the structure. The controls are all analog, no intelligence, and all it does is follow the sun in real-time. So there’s no need for for date programming it just optimizes tilt toward the brightest part of the sky all the time.
  3. Guy Says:
    We had a thunder storm blow in from the north yesterday while the southern sky remained clear and sunny. It was cool to watch the panels tilt down to point at the brightest part of the southern sky as the storm clouds passed over!