My first solar tracker....i'm proud :)

[edy252]

Hi...

This's my first solar tracker....

This's the pdf file for the whole project

http://www.otherpower.com/images/scimages/1733/Solar_tracker.pdf

Here are videos of the finished project in 3gp and avi formats..you can see the tracker looking back at the above lamp whenver i try to rotate it away (i cant wait the whole day for sun ) ... the clicking sound you hear in the 3gp format is the sound of the relays.

http://www.otherpower.com/images/scimages/1733/1.3gp

http://www.otherpower.com/images/scimages/1733/1.avi

Any comments or questions are welcome..........

[Nando]

Congratulations on your effort.

Visit http://www.redrok.com/electron.htm where you will find many circuits that do the job and some with much less energy and with great capabilities, specially the with a H bridge sensor.

Relays, many times, are a problem and with the present type of semiconductors now available, my suggestion is to use them.

Nando

[willib]

cool video

nice work..

[claude]

Good job. I recently made a tracker myself, using red led's instead of LDR's. No relays, only transistors. I used the circuit from  http://www.redrok.com/electron.htm and I had the same problem when the sun was down, the tracker remains rotated towards west. Next morning, the eastern sun wasn't noticed by the LED's up until noon when the tracking kicked in. I solved the problem by using 6 LEDs, three for each side, at different angles, to cover 180 degrees. It now sees the sun wherever it is.

If you're interested, I can post some pictures.

Claude

[TomW]

Claude;

If you're interested, I can post some pictures.

Please do.

Cheers.

TomW

[edy252]

Hi...I'm definately interested in some pictures...

[rossw]

"After the sun is down I 'm planning to use another circuit along with this one ;it's actually a small modification of the automatic night lights. When this circuit senses that it is dark,it will deactivate the tracker's circuit,and give a 2 or 3 seconds pulse to the motor to rotate it eastward"

Might I suggest that a simpler solution to this is to SLIGHTLY bias the "dead band" of your tracker to be slightly off the zero-volts mark. If your two LDRs are mounted slightly crooked compared to the panel, they will be "slightly" offset one way to get "balanced" when there is sunshine.... however when it is dark and both cells are high resistance, the circuit will drive towards the east all by itself. (You will need limit switches on the motor, obviously!)

If the LDRs are offset the right amount (to the west of course!) the panels will be facing the sun.

Just my 2c.

[claude]

Here you go then. I only made the tracking module (I like working with interconnecting modules) and I tested it with a battery and a geared motor + the limit switches. Turned out that 2 wires for the motor + 2 for power + 4 for limit switches ment I needed 8 wires out. Problem solved using a 9 pins serial connector.

The case is a inkjet cartridge. I will waterproof it once it sees action. I still have to do the rest. A good idea seems to just fill the cartridge with hot glue, in small amounts followed by cooling breaks.

You can see the LEDs coming out of the cartridge. 6 Led's in total, one pair is on the side edges.

Here's the serial connector

That's the redrock circuit and the wires that go to the LED's. The original circuit had only two. I used 6, paralelled in three pairs

That's all. The tests I did in full sun confirmed the 180 degrees sensitivity. A better idea is to use a cosmetic cream plastic box, the kind that's round, with a threaded lid. Then the Leds would be arranged in semicircle in 5mm holed drilled on half the side of the box, the serial connector mounted on the lid, the threaded sealing would already waterproof everything...

I hope someone will understand what I mean. I'm in a hurry and my English usually takes more time.

Claude

[dinges]

Interesting. I've been planning to build the Redrok tracker myself, for this PV polar mount:

http://www.anotherpower.com/gallery/PV-tracker

I find the fact that it didn't go back East at night interesting, though I wonder which  Redrok tracker exactly you built (there seem to be a -lot- of different versions on his site).

The one that I had in mind used 4 LEDs, I think it's version 3. I redrew the schematic so I could understand how it worked (the original drawings are near-meaningless to me):

http://www.anotherpower.com/gallery/dinges/redrok_tracker_redrawn_corrected

Could you detail exactly which version you built ?

[claude]

Mine is "LED5S12V Simplified LED low power tracker".

I'm not very good at electronics and this one seemed doable to me:-)

Claude

[ghurd]

How many channels does that one get?

[claude]

All right, that's enough :-))))

Desperate times call for desperate measures...

Claude

[dinges]

Thanks.

[dinges]

I only noticed now you used red LEDs. I understand that the Redrok trackers use green LEDs. The difference in bandgap voltage between the red and green LEDs may possibly account for the fact that your tracker didn't automatically get back to East at morning ?

Anyway, just a head's up w.r.t. to using the correct colour LED, even though they are not emitting light.

[claude]

Yes, I initially tried green leds. It works just as well but at the moment I had only 2 of them around. I took a meter and measured the output of red ones and I found out they are much better. (redrock site says 1.0-1.4 volts but I couldn't get thatr much out of mines, the green ones put out 0.5V max while the red puts out up to 1.8-2V)

The tracker made with green leds faced the same problem - with only two led's there's a matter of sensitivity angle. I noticed that to be around 10 degrees. So I used more of them (but red ones) and I got 180 degrees sensitivity. I guess the overall output is enough to move the tracker in between the sensitivity angles.

So I highly reccomend clear red ones, the kind with a high light oputput.

[dinges]

Ok, thanks for the information. Will measure the bandgap voltage myself as well and compare.

However, when you say that you used LEDs with a high light output, it makes me wonder whether you used LEDs with a narrow 'angle', i.e. that radiate most of their light in a narrow bundle of, say, 10 degrees.

If you did, it might hamper functioning in reverse mode as well, as light sensors, that they only/mostly gather their light in that small beam as well, thus requiring multiple sensors to cover a portion of the sky (for return-to-East to work).

Just some things that come to mind. Not all LEDs are created the same.

Maybe Ghurd can chime in, he's the in-house guru w.r.t. LEDs. But, he's never around when you need him...  

PS: just measured a few LEDs (the sun was shining so there was no excuse not to):

Green LED (in green case, not transparent/'white' case): 1.45-1.5 V

Red LED (in red case, not transparent): 1.05-1.15 V

Red LED (in transparent case): 0.90 - 0.95 V

Yellow LED (in yellow case): 0.60 -1.45 V (?!)

White LED (in transparent case): 1.95 - 2.00 V (high eff. LEDs, narrow radiating angle)

The yellow ones seemed to have a huge range in output voltage...

Also, I noticed that for most LEDs, the output voltage varies very little when pointed directly to the sun or not; made about 0.1-0.2 V difference, expect for the high-efficiency white LEDs, where there was a sharp drop at off-angles.

This also could be due to the case they were in, being possibly wide-angle LEDs. I know the white LEDs have an extremely narrow radiating beam (very bright, but narrow beam) and only when -exactly- pointed to the sun did they output 1.95 V; at angles slightly off voltage dropped very rapidly. So, I expect that not only colour but also the beam radiating properties of the case have a major impact on how the tracker performs.

Regards

[claude]

All this proves that LED's are not equal. My measurements came out way different. But I found out the tracker is very forgiving when it comes to substituting parts so once the board is made, different leds at different angles can be tested (even with a digital meter connected to the output, it will show -V when the polarity changes).

And yes, Ghurd would come in handy but he's only interested in TV channels lately. :-)

I was thinking the same thing - narow light angle out = narrow generated voltage out. But wider angle led's were not so good as those narrow ones. The output voltage was very small, under 1V. If you take a look at redrock page, his latest kit also features 4 Led's pointed out at different angles. That must have the same cause.

Two led's are OK if the circuit would have a return-to-East feature when the sun goes down. Then the two of them would face the sun at first hour in the morning and would track it all day. But if the circuit relies entirely on the sun's position, you should get ready for extra leds. There's no way I could convince mine to see the sun that was behind them (fully turned 160-180 degrees away from it)without additional ones. But I think it is worth it. Led's are not that expensive. NPN's and PNP's either. The hardest part was to find the exact resistor values but I learned that the circuit can deal with a lot of changed values before quitting.

[ghurd]

Nicely done Edy.  Nice write-up too.  It got people excited about tracking!

Peter,

Being a bit psychic, I would say Claude's red LEDs are expensive, crazy bright, 630nm, and 30 degrees.  

I bet the other LEDs Claude tried were salvaged mostly from computer peripherals, with a very wide viewing angle, low MCD rating, non-water clear, and diffused.

Diffused is probably the main thing to avoid, next being anything not water clear. Guessing.

T-1, 3mm, white LEDs with a wider viewing angle, 35 degrees, are becoming a bit more common.  Might be worth a try.

Many of the `extra super-duper bright' 5mm have a beam closer to 7 or 10 degrees than the advertised 20.

G-

[jimjjnn]

Ghurd,

Just curious. How does sunlight effect the plastic lenses on LEDs? do they get foggy?

[ghurd]

Good question.  I'm not sure.

I don't recall any being foggy that looked like UV damage.  Some get `hazy' on the surface, maybe from acid rain?

If they do get foggy it takes a long time.

I have a bank of 40 of the same red LEDs as Claude used. They are semi protected from direct rain, but get a lot of direct afternoon sun, nearly straight into the fronts.  Guessing about 3 years so far.  Still look fine, so I guess I would not worry too much about it.

I think most LED's plastic lenses are actually some kind of epoxy, if that makes any difference.

G-

[jimjjnn]

I wouldn't think acid rain would be much problem as most acids now days is packaged in plastic bottles.

Could be wind driven particles that are more of a problem.

[claude]

Oh my god Glen, how did you knew that?

It's amazing how you guessed what led's I used :-O

Ok people, we clearly hijacked edy's post.

It's clear there is a tracking fever around here and edy's tracker triggered the event. But let's not forget that while we're debating leds to use with the redrock tracker, edy sits in a corner crying out "what have I done..." :-))

Claude

[kimhaur]

hi edy252.. ur sun tracker vry cool.. my final year project is vry similar to what u did, construct a sun trakcer with LDR. my problem now is how to setup a stepper motor.. can u help me??

Thanks...