Simple Solar Tracking circuit

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I have looked through redrok website, now and up to 12 months ago, and found it extremely informative. The only problem is the page is extremely long and has so much information on it, that the average person looking for a solar tracker, would find it difficult to find the best one for his purposes.
However, since we now know the designer of the articles is available for guidance and assistance, this would be a good point to add to the top of his page.
Many of the circuits are HIS as they have never been presented before and they all use readily available parts. The price of his kits is the cost of parts plus the cost of the PC board, so he is providing a very good service.
I don't see anything wrong with designers supplying back-up kits. The thing I don't like is a project being designed and the author leaving it for the reader to scrounge around for parts in the hope the circuit will work. Most of these circuits fail to work. I can give you dozens of websites that do this.
More designers should be encouraged to present projects and supply back-up kits. After all, they have gone to the effort of producing a PC board and the cost of 10 boards is little more than the cost of a single board. (I am talking about PC boards made in China or HK) and others can benefit from this effort.
 
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seeing that I started this thread I feel I can say this : please stay on topic (helping me with solar circuits) and quit messing up my thread... lol
 
Hi Duane ... thanks for the info ... I have visited your long pages many many times... ) ... i checked out the inline and reciever axis heliotrackers but didnt find anything resembling my idea (I may not have explained it very well) I am still working on it and will post some results here as soon as I have some )
 
There aren't many options for heliostat mounts.
1. The classic vertical axis, used by the big guys. Usually tracked using computer computation, but works well with simple dual axis inline trackers.
2. Receiver axis can be tracked with simple dual axis inline trackers and the the mechanical half angle device. But can't use an inline tracker.
3A. Single mirror polar axis can be tracked with simple dual axis inline trackers. However less suitable than vertical axis.
3B. Coelostats, 2 mirror heliostats, can be driven with simple constant speed clock drives. (OK, some seasonal correction is needed.)

Here is a tracker design that is quite similar to the first schematic presented in this thread.
Electronic Projects

Duane
 
you can find the PCB artwork here ... I had some made by futurlec for about $1 a board ... **broken link removed**
 
I think I have finally figured out how to use this circuit as a heliostat... basically reverse the led sensor array so the leds are facing towards the axis of rotation... use a small narrow mirror to reflect the sun back onto the array LEDs... by aligning the sensors null point with the target and reversing the positions of the east and west leds the circuit will rotate the mirrors reflection to the null/target ... I will post some pics once I have it built
 
Simpler Solar Tracking circuit

Hi helpmonkey;

Yes, this is what I call an "InLine" heliostat tracker. (See a post above.)

Here is another simple solar tracker I designed about 10 years ago. However there weren't suitable low cost parts for making it then.
ledblue

I developed the circuit last fall and this winter. It works very well. Please don't substitute Q1 & Q2 IRL3708 MOSFETs. These have particularly low gate threshold voltages and work nicely with blur LEDs. Q3 & Q4 are not critical.

BTW, it would be nice if you gave me credit for inventing the use of pairs of LEDs for sensors in solar trackers on your web pages.

Have fun!

Duane

--
Home of the $35 Solar Tracker Receiver
LED3X Solar Tracker Assembly [*]
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Energy (the SUN) \ \ \ / / |
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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) ===
 
sure Duane ... ill also add a link to your site in our greenlinks section... any ref to my site from yours would also be appreciated ... all the best
 
Hi, I'm new to this all too, and am not very good at electronics, I only know a few basics and that's it. Can anyone give me an 'Idiots Guide' to building a simple solar tracker, I have circuit wizard so can get a circuit boards printed out at college and am ok at soldering, but have read so much am completely swamped with information. I would like to mount up to 10 3"x3" solar cells (from broken solar garden lights) at about 30 to 45 degree angle on a a rotational platform. I was hoping to use some of the cells to power a battery pack for the motor and the rest to charge a phone mp3 or another battery. I'm sure it's possible, I just don't know how. Can anyone help?? Thanks
 

Hi cyberhoiney007

I have certainly been there done that recently. I had a project where I had designed and manufactured an electromechanical solar tracker device. It was a MEng level individual project completed last month. Its a working dual axis solar tracker device that I have built. I have relied on easy electronics, just few OP-AMPS, transistors and relays have done the job for me. No complicated micro-controllers or stepper motors etc. Just a couple normal 12 Volts DC motors with extremely low rpm ratings have done it.

what exact help you would require? I mean you have asked for a complete guide and I can provide you information on what I have done but I have used a PV panel instead of what you have proposed you would like to use in your project?!?! I have'nt used "10 3"x3" solar cells (from broken solar garden lights)" in my project if you know what I mean.
 

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Hi Prem25,
Thanks so much for your quick reply, this will be the second time I've written this! woo ya for IE! Anyway, your design is really about the same as what I am aiming for, but because of my technical know how; well lack there of, I was only planning on a single axis rotational array set out the same as yours but at a fixe angle of between 30 and 45 degrees for maximum solar exposion. This is my final of 2 year BTEC (uk) and am off to UNI in september (woo hoo!!.......terrified much!!) so want to make sure I get the Distinction I have been forcasted!!
Anyway the cells are upto 2v, 30 mA, 0.06 watts (got spec from net) I currently hav 10 viable one but can get more (yay for freecycle). I have access to a PCB printer, 3d printer and lazer cutter (aren't we lucky!) I also have CAD, solidworks and circuit wizard. I have put a few of greenwatts.info circuits in and circuit wizzard doesn't have some of the components and symbols so am a bit confused! (Doesn't take much!). So any help you can give (simple as possible!! lol) will be fantastic.
I want to use some of the cells to charge an mp3, I've seen this on youtube and it looks easy enough, and the rest to run the tracking system. So really any schematics walk thru's, circuit diagrams, components list anything really (and everything lol) you can give me will be absolutely great. Can't thank you enough for your fast response and offer to help.
By the way have you just finished your degree (any good at maths lol)
Thanks again
 
Since your interested in a single axis tracking mount there is little reason to use a "Vertical Axis" tracking mount. It's much better to use a "Polar Axis" tracking mount.

A Polar Axis mount is escentially a Vertical Axis mount tilted over so the axis is aimed at the cestial pole, the north star if you will. The angle of the north end is up from the north horizon by your local latitude.

One of the simplest solar trackers you can make is this one. No opamps or computers needed
Electronic Projects
**broken link removed**
This works from quite low voltages and drives small low current motors.
The sensors are blue LEDs. Please don't substitute Q1 & Q2, the IRF3708 N-chanel MOSFET transistor.
Q3 & Q4 can be most any P-chanel MOSFET.

Have fun!

Duane
LED3X Solar Tracker Assembly
 

Hi cyberhoiney007

I think I understand now where you coming from. I would provide you my report via PM and can advise you the following steps (that I took myself as well) for the project:

1. Get an idea of what size and weight the solar panel / cells would be. Like in my case it was a PV panel purchased on-line. The manufacturer gave me weight and rest dimensions and so I was able to design it on Pro/E (CAD software) and also because of the weight I was able to do the calculations for torque requirements.

2. Calculations for torque requirements- You cannot avoid and have to do this either manually or using the high end CAD software program because these calculations would give you and idea of what rpm / torque / etc. rated motors you would require for your panel (solar cell unit) to rotate. Bear in mind the calculations should not only consider the panel (the 3'' x 3'' solar cell unit in your case) but they should also account for the support hooks or any other material used as the motor would potentially be rotating them as well if you know what I mean. Calculations are fairly simple, you should know the mass and the distance of the mass from the axis of rotation. This would tell you the inertia and you may assume a very low angular acceleration value (as the panel would move really slow). Multiplying inertia to angular acceleration would yield the minimum torque that motor should offer and hence the unit would be able to rotate. You may find more in details and torque formulae in the report that I will send you.

3. I designed everything on CAD so that it can help my university's technicians in manufacturing / development stage. Because of the proper designs I was able to show and request my technicians what I wanted and they were able to bring the design to reality. I used a worm gear in mechanics as in a worm gear the gear can be rotated by the worm but otherwise. And hence my east west circuit didn't required stalling current as well. The worm gear mechanics solved the stalling issue. If you see the panel that I have (or in fact every solar panel on a tracker) only goes 180 degrees in one day and also this rotation is distributed evenly throughout the day. That means extremely low speed, hence this was considered as well at the design phase and I ordered extremely low rpm 12V DC motors on-line. Although I think yours is not going to go 180 degrees as you would have the unit poised and inclined at 45 degrees or something and just the base would turn the unit. So you might require to tweak the torque calculation as per your needs.

4. Electronics- I had used National Instrument's MultiSIM software to simulate my circuits so that I can be sure that those circuits that I am going to use would definitely work. I used two different circuits i.e. north-south and east-west. Both were simulated on MultiSIM and tweaked as per requirements. These circuits were then made on Eagle Schematic editor i.e. PCB design software. Eagle is a very effective and easy software to design PCBs from their schematics. Simulation made sure the circuit would work and then the circuit was drawn on Eagle (my university uses Eagle) schematic editor. The same circuit was then transferred on to Eagle's board layout so the PCB can be designed. After the PCB was designed properly (layers not crossing/ components not overlapping) the files were emailed to my university's applications unit and they manufactured and drilled the PCB for me. I had placed the components and soldered them, this made PCB come to reality. I had used three PCBs namely East-West, North-South and sensor array.

In the design phase I had also made sure I know already where my PCBs would go and they would probably not come in way of any other thing/component/etc.
And oh yeah, I had used 4 CdS (Cadmium Sulphide) LDRs for the sensor array and the position where they would sit on the PCB was also precisely calculated by using the shadow blocker's dimension (outer diameter in my case) and the vertical distance between the shadow blocker and LDRs.

I can go on and on and on as this is just a start. By the end of the project my logbook had been extremely thick but thankful I am because without this logbook my project may not have been successful at all.

I would propose you give it a go as per the steps I have discussed above and see how you get on with it. But yes let me know should you require any further advise any time.

And nope I still have my last 5th year left on the MEng profile. I believe I am okay with Maths though.

regards
prem25
 
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You have forgotten the largest load on the panel. Wind load is by far larger than simple weight from the panel or even from snow loads.

I use the local building codes. In my case, Minnesota, this is 10 lbs/ft^2 due to horizontal wind speed. This is equivalent to about 90 mph. I understand that in Florida it is 15 lbs/ft^2 at 105 mph. This force taxes the whole mechanical system.

In addition I design for a dynamic torque of 5 lbs/ft^2. I call this the "Stop Sign Effect" which causes flutter when vortexes shed alternately from opposite sides of the panel. I apply +5 lbs/ft^2 on one side and -5 lbs/ft^2 on the other. This really taxes the drive components.

I generally recommend a drive train with a total gear ratio of 100,000/1 or more. This gives slow motion, a good thing, and high torque with relatively small motors. A nice example motor is the Grainger 2L003. See:
2L003. 1/2 rpm, 7189/1, 0.1A. 50in#
Gearmotor, 0.5rpm, 12vdc - Gearmotors - Gearmotors - Power Transmission : Grainger Industrial Supply
This has 7000/1 in the gearbox alone.

I noticed that there is no hysteresis, Schmidt Trigger Action, in your schematic. This can cause oscillations around the set points which can cause excessive power dissipation in the transistors. MultiSim should have shown this. The solution, which I haven't simulated myself on your circuit, would be high value resisters, maybe 10MOhm, from the OpAmp outputs to the + inputs. In addition a small capacitor, maybe 1000pF, across these resistors.

Have fun.
Duane
Red Rock Energy
 


Hi Duane

Thanks for writing.

Wind loads have certainly been accounted for and they are in the report I PMed cyberhoiney007.

As far as the oscillations are concerned, my east-west circuit does not produces any wobbling of the panel because of intermittent shadow (birds, clouds, etc.) reason being I have used capacitors that time the circuit and hence only and only when the shadow comes over one of the LDRs (Sun goes West so East LDR to be exact) and remains there for a while the circuit would come in play otherwise it remains as it is. Rest I have used limit switches as well to bring the panel back to east every evening for the next day tracking.

I have tested the whole unit at my uni place under sunshine and it is working flawlessly.

regards
prem25
 
Hi Duane,
As I am only at college and this project is only a small begining as I am off to uni. I'm only doing a small unit as I only have those small cells (very expensive to get good cells in the UK) So I have used what I can get my hands on. **broken link removed** This is the design I'm aiming for, it's only a box file and is more for a demonstration at college of what we can achieve with solar power and how tracking can increase efficieny etc etc. As it is only likely, at this stage to be used in the college and in the garden to charge my mp3 or phone I don't need to worry too much about wind and materials. In the image the holes are there just for the wiring, and the squares are these to accommodate a few heat sink designs I have done. I was thinking of mounting the LED's on the top edge of the box lid, but as for what motor to use, what circuit to use..............i'm lost! I wasn't even sure what you meant by a polar axis mount?! I do hope I catch on a bit faster when I go to UNI!! In my defence I've been looking at a way that cells can absorb more of the solar frequency, and using fresnel lenses and mirror . As for components I think the college uses Rapid | Distributors of electronic components, electrical products and educational supplies, I guess I'll use them as I don't know anywhere else in uk. Again thank you so much. Valerie
 
I didn't see this answered anywhere

prem25 said:
Hi Colin55,
may you please advise where the third pin of variable resistors 20K and 100K is going? should you know!
Thanks
Click to expand...
We all have to learn from the start-These are usually 3 pin adjustable , the center pin is usually connected to the wiper arm. As you move it you get more resistance on one side pin and less on the other side pin. Like these say
**broken link removed**

So here the center pin and one side is soldered in and adjusted to the right resistance value
 
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hi prem25
I am a college student who is going to build a dual-axis solar tracker for my project within this month.
I have read everything that you posted in this thread, I believe that your design is the most suitable information for me through out all my searching on internet and forums.
Could you please help me with the solar tracker? Can you send me your report via PM?
thank you very much for your help.
 
I put together this cir from AND what is happening is that the East motor turns on and dose not shut off.This is on my bench.What is causing it from not reversing the motor when I cover one of the photo cells.I have adjusted the pots.The west relay just wont kick in. Im going nuts, Just begining to learn what the components do also.I can put it together by the schematic.
Tks For any help.
John
 
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