Can you help?

[David HK]

I never expected that my simple articles on the Sun Tracker would generate such interest. If I had known, I would have set up a diary.

Unless "Tom" advises otherwise, I have a Part 3 to add to my last posts sometime next week.

Suffice to say that some of the people that come into this web site are very clever indeed. To substantiate my claim (and that of others) that a solar panel assembly photo voltaic panel) tracking device makes the best use of the sun I would like to put myself in a position to monitor it.

Does anyone have any circuit ideas (proven or otherwise) whereby I can use my computer to record DC volts on a nominal 12 volt system, Amps, and Watts on an Excel file?

This should put facts on the table for all to see.

For a moment of interest, at 08.30hrs this morning (HK time) the sun was so magnificent, that I quickly wheeled out my test bed assembly and set it up. The power output from my two solar panels was 11 watts. Later in the morning I achieved a 'best ever' of 13 Watts at 11.30 hrs. The sun was due overhead at 12.30hrs and then cloud arrived!

I look forward to any help, or ideas, that people may have.

David HK

[Bruce S]

David HK;

   Perhaps as a start you could disconnect one of the two panels and with the sun shining take readings from each of them while the one is tracking and the other merely pointed at the sun?

Thoughts?

Also; There's a few circuit out there that allows you to take multiple reading from different items that will plug into the legacy type parrallel port. Otherwise you may need to have more than one serial port available.

Bruce S.

[Gordy]

David'

I can't help with the computer hookup. But when you get that figured out could you do a side by side comparison with another panel of equal size but stationary mounted? That would answer the debate going on as to weather the tracer is the better /cheaper option, than adding more panels. I think the tracker is the cheaper option if it is home built.

You probable already figured it out, but the difference in your #'s is due to the filtering effect of the atmosphere, less filter at solar noon and more filter as the sun is closer to either horizon.

Gordy

[WindChopper]

David HK

For a "non-build it" version you might want to try:

RS232 Serial ( if you still have a Comm Port - they ARE getting rare ! )

DI-194RS Starter Kit, 4-Channel, 10-Bit, Data Acquisition Starter Kit,

$24.95 USD

http://www.dataq.com/194.htm

or

USB

DI-148U Starter Kit 8-Channel, 10-Bit, Low Cost USB Data Acquisition System

$49.95 USD

http://www.dataq.com/products/startkit/di148.htm

It comes with a slow response ( 240Hz Max ) Data Acquisition software package

which is fine for what you are trying to do.

( FREE ).

http://www.dataq.com/products/software/acquisition.htm

I think that these prices are "Dirt Cheap" except that you live in HK where

I understand Dirt is NOT Cheap ( got to love those Real Estate values ).

I am also not sure what HK shipping or duties might do to that price.

No, I do not own shares in or ....... but I own two of the DI-194RS, they

come in handy for quick and dirty measurements.

(When I went to check the links, was the first time I noticed the DI-148U

USB version - 8 analog channels - that has possibilities! )

10VDC full scale, so you would need to pre-scale the inputs with a voltage

divider 2:1 (20v FS) or 3:1 (30v FS).

If you are a Picaxe basher and know BASIC, then that would be the obvious

choice.

An 08m with a voltage divider (internal ADCs are 5v FS) so a voltage divider

4:1 (20v FS) or 6:1 (30v FS) would be called for.

( http://www.rev-ed.co.uk/picaxe/forum/ for a good background )

Use a series resistor ( 1 ohm at 10-20 watts ) to a fixed load ( either a

load resistor or an appropriate light bulb as batteries vary their current

demand depending on their state of charge ).    Measure the voltage on

either side of the 1 ohm resistor will give input volts and load volts to

calculate current.

Russ

PS I just went to try the "New" software with a USB/RS232 Conv. and the software does not like my computer!   Now I just have to find the original CD with the "Old" software to see if that works on this computer.   Like they say .... no good deed goes unpunished.

[dinges]

You might want to try to find an Amp-hour meter somewhere. I haven't seen any cheap ones (the ones at my boating supplier are 500 $ +) but I remember a version somewhere for model aircraft that was pretty cheap.

Can't think of the brand or find the link at the moment. Hopefully others can help here. Such an item would be a generally handy thing to own in RE applications anyway. Sort of like a fuel gauge for a car.

With one of them, you'd have an easy way to find out how much energy is produced at the end of the day (not really a logger though). One could compare an average of several days of tracking with non-tracking.

Looking forward to your results.

Regards,

[dinges]

Just found a link...

http://astroflight.com/store/store-type-tem.html?item=products:af-101&sid=0001WxxseUJjcUc5kw3S11
6

Price=55$

Hope this helps.

[asheets]

I've seen in the Jameco catalog a PCI card that would handle DVM duties nicely.  There was also an article a few years ago in a magazine who's name I can't remember right now that built a voltage sensor into a USB jack.

Probably another simpler way would be to analog to digital converter up to a serial port.

Way back when, when Atari computers had the capability of handling "paddles" on the game ports (which were just big potentiometers), I found that you could bypass the pots and feed in your own resistance, or even DC if you kept it under 5 volts.  I haven't seen anything like that in years though...

[SamoaPower]

David,

Rather than having to have a computer on during the data collection hours, you might consider using a self-contained data logger.

A four channel stand-alone logger module in the HOBO series is available from Onset for about US$100. Basic analysis software is available at low cost.

Depending on sample rate, it can collect data for up to a year. Periodically, data can be dumped to a computer for analysis.

Seems better than tying up a computer long term.

[wpowokal]

David, you will never put the track or not question to bed reguardless of what information you gather, people will believe what they want, I did the test some time ago and posted here.....

http://www.fieldlines.com/story/2005/2/1/0713/31693

I know what I can achieve in my situation/location and that's what matters to me, basically if you can keep panels pointed directly to the sun you have full output, that simple. Arguments about maitenance/cost are relative to individuals and their ability and funds, not the possible output.

allan down under

[TomW]

Alan;

I have to agree pretty much across the board. To me maintenance is pretty simple some checking for secure nuts and bolts a bit of grease and hose em off when the biggest bird crap in history splats right on the panels. People do buy in to whatever reality they wish and no amount of proving will change it.

Perhaps it is you and I?

Carry on....

Oh haha.

Cheers.

TomW

[RogerAS]

Hey all,

I will finally get into the game here (hell of a 6th man).

I do tracking via my own design. My panels and batteries are happier. Going on 2 years with no faults, mechanical or electronic. I use 555's a LM334 with 3 CDS cells and a few other parts, I have a file if you wanna look.

I'll post picts soon of my setup

I've never seen the sun track to the east, and my design focuses on this fact, pardon the pun:-). My setup draws much less than it adds to the good.

Tracking helps when your PV's are small or large, by my perceptions.