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Wauw - most interesting thread. Some time ago I looked at solar tracking circuits and found some. However, they were more complicated - in my perspective this is accessible. Thanks for posting!
Here is what I posted as a comment on Wayne's (HelpMonkey's) **broken link removed**
Wayne, I see that you are touting the circuit I posted for you on www.electro-tech-online.com as your circuit #4, with no attribution, and with an implication that you designed it. I don't mind if you market it as a kit, but it would be nice to if you had left my name on the schematic diagram, and acknowledge where you got it.
btw- This circuit does not work on the same principle as your CDS circuit #3. In fact, my circuit solves the HUGE problem that circuit #3 has, which is that the motor drive current NEVER goes to zero, causing the batteries to discharge even when the panel is at rest.
Honestly, these "simple" solar trackers with discrete components are vastly more complicated than a simple microcontroller. A microcontroller will allow you to adjust to prevent oscillation, avoid overdriving past the end of the mechanism, and reset to the east in the morning with no problem at all. There's no complicated "how am I going to do this with components?"
Note that the value of the tracker's additional power is limited. What most installations have found is that the cost of the tracker with moving mounts- and maintaining those mechanisms, which tend to rust and jam after spending months and years outdoors- is not worth it. It is cheaper to install more fixed panels than to install trackers on each panel. You'll get more output per $ in the end.
And you might say "but I only have X sq ft of roof, and can't add more panels, a tracker will allow me to get more output per sq ft." That's actually not correct! The roof gets a certain sq ft of sunlight. A panel which is turned towards the sun to capture more sunlight casts a larger shadow on the roof, so the panels must be spaced further apart to avoid shading each other, which is bad news! And that spacing is a loss of area which applies all day- at noon on a south-facing roof, the panels cannot walk across the roof to bunch up and allow another panel to jump into the roof, right?
So, actually, a roof covered with panels with no tracking can be placed adjacent to one another, and actually will produce MORE power than a roof covered with panels that had to be spaced for the tracker. And costwise, it's cheaper than a tracker.
The case for a tracker is when you have extra roof space you're not going to use, and a limited number of panels, but oddly enough have money to spend on trackers for the panels but not on more panels.
MikeMl ... I am in no way touting that I designed this circuit as you can clearly see from my post here... I would be more than glad to give you credit for the circuit and again thankyou for your excellent help... I am making the circuit available to buy but at cost I would rather not but I just get so many emails requesting a pre-built or kit for the circuit... I am not sure who else posted the rude comments referring to this forum on our comments section but I did not delete their comments and I did not delete yours (I do not know why yours was not posted) ... again I will be glad to give you credit and I appologize for the misunderstanding.
Oznog you make some good points but there is more to consider... first of all tracking is not just used for PV panels its also used for solar heating, concentrating and solar cooking... also there are situations where people use a single solar PV panel to keep a battery charged for example a boat lift and tracking can make that type of system work much better... there are also situations such as marine applications where there is simply no room to add extra panels ... you must also consider northern and southern locations where tracking can substantially improve PV performance and aids in the removal of snow from covering the panels... as for price trackers can be made very cheap and with minimum maintenance last for years and years. So yes in certain situations it may not be adventages to use trackers but in many other situations it is very adventages.
I have posted design credit for the circuit and again I appologize. I found your origional comment was posted and is currently on the 3rd page of comments... I hope you will still offer your expertise going forward?
As OZnog said, it is much better to use a microcontroller to do all the work as there are so many variations to consider. These can all the done with a micro ($1.50) and a few parts. You can even use a $5.00 servo to do all the work as it has inbuilt gearing and use the solar panel to give you feedback. You can make the whole system "intelligant," for no additional cost, as it will search back and forth to pick up the best position. It will also "look" in the morning for the sun. All at the cost of 10 microamp quiescent.
Another good source for a powerful geared motor is an electric screwdriver. It has a 3v motor and (in-line) sun-and-planet gears that produce enormous torque. These screwdrivers cost less than $10.00 amd saves all the frustration of trying to design and build a gearbox.
Each sun-and-planet section produces a reduction of about 8 to 9 to one and you can add more by buying two drivers. They are the most amazing and interesting drives of all reductions - to think you can have input and output on a single alignment. Pull one apart and see how beautifully they have been desinged. The motor is also a work of art. Possibly the most powerful 3v motor you can get for $3.00
Here is what I posted as a comment on Wayne's (HelpMonkey's) **broken link removed**
Wayne, I see that you are touting the circuit I posted for you on www.electro-tech-online.com as your circuit #4, with no attribution, and with an implication that you designed it. I don't mind if you market it as a kit, but it would be nice to if you had left my name on the schematic diagram, and acknowledge where you got it.
btw- This circuit does not work on the same principle as your CDS circuit #3. In fact, my circuit solves the HUGE problem that circuit #3 has, which is that the motor drive current NEVER goes to zero, causing the batteries to discharge even when the panel is at rest.
As OZnog said, it is much better to use a microcontroller to do all the work as there are so many variations to consider. These can all the done with a micro ($1.50) and a few parts. You can even use a $5.00 servo to do all the work as it has inbuilt gearing and use the solar panel to give you feedback. You can make the whole system "intelligant," for no additional cost, as it will search back and forth to pick up the best position. It will also "look" in the morning for the sun. All at the cost of 10 microamp quiescent.
I could write a program for a PIC12F629, to take the place of the op-amp, and provide PWM into BD679 transistors. The advantage would be an "intelligent" tracker that would look for the sun in a sweeping motion and remember the maximum input for the arc.
The output would be a $10.00 screwdriver with planetary drive.
I am working on another project at the moment and this will be next. The whole circuit would cost less than $15.00
your absolutly right about the power screwdrivers ... you can also use power drills as they also have planetary gears...BUT... you must also make a slew gear arangement to prevent back drive... a worm gear (which can be made from any bolt or threaded shaft connected to the chuck of the screwdriver can then rotate a spur gear which is connected to the tracker shaft... this provides a locking mechanism as the spur gear cannot rotate the worm gear and therefore the drive motor backwards. Here is a video it uses a SkilTwist screwdriver with slew gear and Mike's circuit--> https://www.youtube.com/watch?v=_4Vu-RBQBEc
As for the microcontroller I agree it is better but far far far from simpler... most people are not very adept at simple analog electronics let alone digital systems that require programming.
I am attempting to evolve this type of circuit into a heliotracker ... I have been able to do it mechanically with very good results but would like to accomplish it electronically. Any ideas or input would be greatly appreciated.
What is the business end of the heliotracker doing? Heating water?
Seems like you could use four thermocouples to detect the solar flux just before it hits the heating chamber. Four tiny thermocouples would sense the solar beam without casting much of a shadow (or blocking much of the solar energy). Configure the X and Y pairs of thermocouples in inverse-series similar to what I did with the LEDs (which were inverse-parallel). Basically, you would build two identical trackers similar to what I posted for the single axis tracker.
I have another non-invasive way of doing it but you would have to sign a non-disclosure form...
I did some reading about using LEDs as photo-detectors, and got motivated to try an experiment. I tried some moderately bright red LEDs that I have laying around, similar to these. They are in a water-clear T1 3/4 lens. I do not know their viewing angle; i'm guessing they are the 30 degree variety, because they were bought for indicators.
Shunting an unbiased LED with a 1megΩ resistor, under outdoor illumination on a sunny day, I get about +1.5V anode to cathode, using a Fluke 73 DMM (>10meg input impedance). The LED is directive, consistent with the "viewing angle" shown on the referenced data sheet.
I then connected two LEDs in parallel, which approximately doubled the output voltage, indicating that the current produced by the LED (into the 1megΩ resistor) also doubled. I then reversed one of the LEDs so that the pair is connected in inverse parallel with the 1megΩ resistor, and bent their leads so that their optical axes diverged by about 45 degrees.
The inverse-parallel 2 LED array produces +- 1400mV as the array is panned across the sun, with zero volts out when the optical axes of the two LEDs roughly bisects the angle formed by the two diverging LEDs. Seems like this could be used to drive a Sun Seeker, because the 2 LED array puts out a signal which goes from +1400mV to zero to -1400mV as the sun angle changes.
To construct a Sun Seeker using the inverse-connected two LED array, you may have to put a small baffle that splits the angle between the two LEDs, orthogonal to the sun's path. In the morning, when the array is parked looking at the wrong horizon, the baffle would cast a shadow onto the west LED, allowing the East LED to dominate to drive the seeker toward the East horizon. After the seeker locks on, the baffle would be edge-on to the sun, so the differential mode of the array would not be effected by the presence of the baffle.
Using this idea, I modified your circuit to include a deadband near the balance point, and made it so that the motor switching transistors use a Darlington connection to minimize power dissipation while the motor is running.
Attached is a schematic and a running LTSpice simulation. The Solar Flux is simulated using a current source, which produces a voltage across the LEDs similar to what I measured outside. I use two comparators to implement the deadband region near the balance point, so the motor is switched off cleanly once the seeker centers itself. The transistors dissipate less than 1/2W when switching 1A. Substituting a PFET and NFET for the transistors lowers the part count, if you have the FETs.
Hi Mike ... lol ... I just want to create something generic that can be used for hot water, passive heating, solar cooking etc... I would like to keep it all contained within one device not requiring a sensor at the target... I am thinking of seperating the sensor drive from the reflector drive and using the sensor drive to physically adjust a potentiometer ... now for the reflector drive simply replace the input stage of your tracking circuit (the LEDs) with a voltage deviding arrangemnet using the sensor pot and a second pot which sets the position of the target... this would have to be done for both axis (4 circuits altogether) but is still faily simple... what do you think?
The heliostat control you are describing is essentially called an "Inline" tracker. Whether you have the sensors at the target or somewhat closer to the mirror makes little difference.
See examples of inline trackers at my patents page: Neat Patents
Then do a browser search for the word "Inline".
There is a technical problem with inline trackers in general. There are 2 stable mirror orientations.
1. When the image of the sun looking back through the mirror is centered in the mirror.
2. When the image of the sun looking back through the mirror is positioned anywhere around the edge of the mirror.
Actually, when the sensors are at the receiver, as you are describing, the second stable mirror orientation doesn't happen.
However, they all need to have a secondary tracker to get them pre positioned somehow. The receiver located tracker has the most need for a fairly accurate pre positioner.
There is another tracker method I call the "Receiver Axis" tracker. These can be called "Receiver Axis", "Target Axis", "Spinning Elevation", "Spin Elevation", "Spin Tilt", or "Rotation Elevation". I have a description and example of these at: Heliostat Lighting
And examples of "Receiver Axis" trackers at my patents page: Neat Patents
Then do a browser search for the word "Receiver Axis".
The receiver axis tracking mount has a major advantage as it neither needs a pre positioner nor can it be fooled by secondary stable orientations. The reason is it uses a direct tracker, this means the dual axis sensors are looking directly at the sun, not back through the mirror. My example uses 2 gears and others use a cable and pulley.
Duane
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Home of the $35 Solar Tracker Receiver LED3X Solar Tracker Assembly [*]
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Hi Duane,
With the 5 posts you have done on this forum EVERYONE is a link to your website where you sell those trackers. If this is intended to try and increase your sales then maybe I should throw a few links in here about your previous customers where delivery times and support were just simply non existent. On the other hand if you truly want to be a member of this forum throw some of your circuits in here so members DIY and learn.
I will let you reply to this with a reasonable time frame or ......
I have never solicited sales on this forum. I am a circuits designer. I particularly enjoy solar trackers.
Reply #36 above is a list of relevant circuits that used pairs of LEDs as PV sensors. I consider this innovation to be a "Personal Invention" of mine. Don't worry I didn't patent it even though I could have. Reply #38 was on the subject of heliostat design and sensor placement.
I don't recall 2 message numbers that were related to my stepper motor solar tracker. Someone had posted my schematic, that was fine by me but it would have been nice to have been credited. My response was to help explain why the circuit didn't run when the guy who had substituted a IC.
I thought it was directly on topic. Yes, I do sell some solar trackers. However, if you look at my links you will see that I publish complete circuit diagrams for all of my designs. Including those that I sell. Many of my circuits have been honed over years of trial and error and they work and work well within the constrains of appropriate use.
I welcome anyone who wants to build my circuits to do so. I even answer questions when time permits. Although much explanation is already in the text. I enjoy discussions pertaining to heliostats, a particular passion of mine.
My web pages are full of stuff with which I have experimented and other info gleaned from the net. I consider my web pages as "personal" pages. Hopefully others can make benefit of what I have learned.
Usually web pages devote to "Sales" have little actual content other than prices of their products. If you peruse my over 150 MBytes of content you will see what I'm saying is true. I don't apologize for some things I do sell. I can give away my designs but it would be to much to expect me to give away the hardware also, besides I sell them pretty cheaply for what they do. I have sold over 8000 of my LED3X tracker units. Think of how many people I've enable to make their tracking mounts work.
Anyway, if you wish to ban me that is ok. I trust you can remove me from the roster and remove my posts if you want.
BTW, if you want to see some innovated sensor designs you may want to see this page: Beam Circuits
Most of these are based on using LED pairs for differential light sensors.
Duane
--
Home of the $35 Solar Tracker Receiver LED3X Solar Tracker Assembly [*]
Powered by \ \ \ //|
Thermonuclear Solar Energy from the Sun / |
Energy (the SUN) \ \ \ / / |
Red Rock Energy \ \ / / |
Duane C. Johnson Designer \ \ / \ / |
1825 Florence St Heliostat,Control,& Mounts |
White Bear Lake, Minnesota === \ / \ |
USA 55110-3364 === \ |
(651)426-4766 use Courier New Font \ | redrok@redrok.com (my email: address) \ | Red Rock Energy Heliostats (Web site) ===
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