Solar Tracking is an interesting mechatronics challenge. It is particularly interesting because on one hand it appears very simple, keep the solar panel oriented perpendicular to the sun in the sky. No big deal. A kid could do it. If he could be kept out doors on bright sunny days making adjustments every 15 minutes all day long, as long as there is daylight. Probably a bad idea, surely it would cause a lawsuit for child endangerment or something.
But you get the idea. The point of solar tracking is to keep the solar panel perpendicular to the sun as the earth and sun both move during a year’s time at a given location. And location matters. Depending on what the latitude is, the geometry of the annual cycle of the sun can be very different. Seems simple, but it ends up being pretty difficult.
It also matters what type of solar cell is in use. Traditional silicon photovoltaics do not require much accuracy since the cover layer that protects the silicon diffuses incoming light. +/- 10% in either direction will work. For concentrating solar technologies (there are several), accuracy is much more important. Accuracies of 0.1 degree of angular position are frequently specified due to the fact that alignment is critical to the performance of many of these systems.
What is interesting is the number of different solutions for solar tracking that are currently installed around the world. According to a report done by Photon Magazine, there are over 150 companies worldwide supplying different tracking solutions. Many claim increases of output electricity up to 50% for 2 axis tracking. So why aren’t all solar photovoltaic systems on trackers?
The most widely used systems move as many solar panels at one time as possible using a single motor and gear reducer. This makes sense from a cost engineering standpoint, but there is some risk. If the gearmotor fails, the output can drop off to zero multiplied by however many solar panels are on that tracking system. Notwithstanding, reliability has been good and almost every major utility scale solar project has ground mounted system trackers. Generally these are single axis trackers with a fixed elevation like the Sunpower T-20 (plenty of good video on YouTube).
Every once in a while there is a really novel approach that simply defies description. This one you have to see. Check out Qbotix. It is a small robot on a guide rail the manually adjust solar panel arrays in large installations. Their website is www.qbotix.com and it is really worth a look.