Improving Solar Performance With A Sun Tracker

Guy Marsden tells us about linear actuators for his solar panel tracking system and sustainability.

by Guy Marsden

As someone who is very committed to living sustainably, I have done a great deal to reduce my energy footprint, both by increasing the efficiency of my Maine home and workshop and by adding solar heating and electric systems that I designed and installed myself with the help of friends, neighbors and family. I blog about my sustainable exploits on my website.

It took me a few years to cover the roof surface of my workshop with good solar exposure with 29 solar panels – adding panels as I could afford them. Once I ran out of space on the west-facing roof, I realized there was a little room above the solar collectors on the more optimal south-facing wall of my workshop. This would allow me to place two more solar panels angled out from the wall. When I installed them in March 2013, I mounted the 2 panels to the wall at a relatively steep angle of around 20° elevation in order to optimize solar production in the winter and to encourage snow to shed from the panels. Several months later I realized that I could optimize the performance of these two solar panels by having them adjust their tilt daily to track the sun's elevation.

As an initial test, I changed the mounts on one of the panels so that it tilted out at about 45° to match the average solar elevation of my site and then measured the power of both panels at solar noon in late May. The readings showed that the winter optimized panel was producing 195 W while the panel that was pointing almost directly at the sun produced 224 W - a net gain of about 13%. This convinced me that throughout a solar year I could gain a significant amount of energy by tracking the solar elevation seasonally.

I purchased a couple of Progressive Automations PA–14 linear actuators with mounting hardware and weatherproof boots and installed them so that they could push the bottom of the panel out from the wall and retract it back closer to the wall seasonally. I designed a sun tracking sensor with 2 photocells in a small plastic dome that I mounted directly to one of the panels. It sends signals to a control box I built to drive the motors so the panels face the sun. Originally, I left the system running all day, but it became annoying because anytime a cloud passed overhead the panels would tilt down to point at the brighter part of the sky. The sound of the motors could be heard throughout my workshop, so I plugged the control system into a timer that only operates it briefly at noon every day. Now the panels simply adjust by a fraction of an inch every day to track the changing elevation of the sun. 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 length (my winter solstice elevation is 22.4° and summer elevation is 67.18° here in Maine). My rough calculations show that I am increasing the power from these panels by over 20% annually which is significant.

You can learn more about Guy, his solar tracking system, and his efforts in sustainable living by visiting his website.