Hi. As a thesis work from my university I will be studying solar tracking devices, and the idea is that I also construct a prototype solar tracker (controlled by Arduino) to prove/disprove my theoretical simulations on tracking methods etc.
Now as I understand it the normal most basic way to track is simply to follow a predefined path for the sun or, as I’ve seen on youtube, using photoresistors to determine where the light is coming from. What I will examine in my thesis is slightly more complicated. Since PV-panels are able to produce electricity better from light with a certain wavelength than others, my idea is to have many different kinds of sensors registering different parts of the spectrum, and based on the collected data a weighting process takes place to determine which tilt/orientation would be most effective to produce electricity. One extreme (and unlikely but rather cool) situation that could occur with a system like this is that the tracking device choses to be oriented towards a place that appears to be completely dark to a human, but since its detecting a strong presence of infrared light it would be able to produce electricity anyway.
This may seem a bit ambitious, especially since I am a beginner with Arduino. But if I just stay positive and ask help from the right people I’m sure I will learn a lot in the process and the outcome will be interesting and cool! :)
So just to get my design process going a bit and maybe know what stuff I should order from ebay I would like to ask a few questions that you Arduino experts can answer:
• First of all: is it even possible to ask the Arduino to collect data from several types of sensors and calculate a weighting between them and control a motor based on that? I can’t imagine that this would require a lot of computing power, but it is something that the Arduino is capable of?
• If I use photoresistors for this (is that the best option btw?) will I be able to get an absolute value from them for example: “200 W/m² of a certain wavelength is reaching the photoresistor right now”. Or will I only be able to get some strange relative scale that is difficult to interpret like: “On a scale from 1 to 100 this resistor is getting hit by 50 light right now?”
• It would be good if everything the Arduino measures could be logged and exported to a computer so I can assess the data and what it is doing, it that easy do to and what would be the best solution? SD card connected to the Arduino?
• On videos I’ve seen on tracking devices using photoresistors, they only use one or two resistors. In my mind that doesn’t make sense, how does that work? Wouldn’t you really need like 360 photoresistors (one per degree) positioned in a circle to determine where it is brightest? And that’s just for a one-axis track, let alone dual-axis. Or is there a way to detect from which angle light is coming from in an easier and better way?
• I have been thinking about using stepper motors to control the movement. But from what I understand they don’t “know” themselves how they are positioned, so is it impossible to command a stepper motor to for example “go to inclination 20°”, since it doesn’t know where it is right now, is that correct and is there a work around for that in that case?
• From what I have seen a lot of people are using linear actuators instead of normal stepper motors when building tracking devices, is there any benefit to that or is it just a matter of taste?
Obviously I have millions of more questions but I suspect that I will scare people off if I keep writing on this little novel right now.
Big thanks in advance.