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Thread: Measuring Panel Output. How is it done?

  1. #1
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    Default Measuring Panel Output. How is it done?

    I must be doing it wrong, I have 60W worth of panel, and in full sun I only got 0.94 amp peak over about 13.1V peak over about 45Minuets.

    Here is what I did: Panel was in the sun all nice and hooked up to the charge controller that was doing it's thing...
    On the back, there is a little deal with termanals and ribbons.

    Left and right taps give 12V - Easy. Plugged my meter leads for 10A, went in and measured. Got what I got above. I must have done this about 50 times today - over and over to see what was going on. Untill it got the full sun I was reading 20 to 60 milliamps, then climbed rapidly once the sun came around and faced the window.

    There is a center tap with some diodes on it that gives 6 volts against either outside tap. No idea what to do with that. Should I be measuring there somehow?

    My numbers show I should be getting about 2.744Ah per day available load FROM the batteries after all the inefficiencies, charging, etc. These numbers show I probably didn't even make an amp hour at the panel, and that can't be right.

    So, How do you measure the panel output?
    (And the batteries were near full, if it makes a difference - I read somehow it might, but I don't know the interrelation.)

    I guess since the sun has already set, I'll put a load on it and then take the panels outside in the morning to measure. I can't think of anything else.

  2. #2
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    Only two test you can do

    Voltage open circuit and Current short circuit. Go figure it out yourself.
    MSEE, PE

  3. #3
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    I know what happened - I screwed up the math somewhere, but where?

    After further review I should expect 0.68 amp hours somewhere.
    I know I made roughly 0.8 to maybe 1.2 at the panels - looks good initially, but:

    0.240 amp hours use per day at the batteries.
    Thats a heck of a lot different than my earlier 2.74.

    How do we go from the sun being a thousand watts per square foot, to this?
    I'll sleep on it. I have to have the numbers wrong somewhere.

  4. #4
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    Quote Originally Posted by Crumb View Post
    How do we go from the sun being a thousand watts per square foot, to this?
    You would be better off to go back to drinking. Then you might have a clue. You do not know the difference between a square meter and a square foot.
    MSEE, PE

  5. #5
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    1000 watts per m2 and that is a maximum on the best day of summer.

    Here (and we have good sun all summer) we have an annual average of just over 5 kW/m2/day.

  6. #6
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    I can't get anything from the panel.

    I have tried all 3 meters and only one gives me a voltage at 17, but that's a big meter for farms and whatnot.
    Neither of the other two give me anything anymore.

    I either got a bum meter or panel that was never good for much.
    What really irritates me is it might be both.

    At least they make 5000W panels. I never heard of an M2 but I assume it's military? Gotta be big ones. Have fun with those man! Serious hardware right there.

  7. #7
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    Quote Originally Posted by Crumb View Post
    I never heard of an M2 but I assume it's military?
    At first I just thought you acted stupid. Now I know you are not acting.
    MSEE, PE

  8. #8
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    How to you prove a system works without meters?

    I think I blew up all my meters today. I think they are toast. I am done with it.
    Matter of fact, I don't think I ever had any accurate readings - they all looked bogus to me.

    That means the panels are probably fine, so I won't sweat that.

    I want to be done with this project.
    Automotive voltmeter from a dashboard shows just shy of 13V in the sun on the batteries. That proves the meters were the problem all along, actually.

    That's good enough for me, but should I expect any problems with it? I really don't want to have to mess with it again.

    All my indications show everything is fine besides bogus meters so Ill eventually get a nice used one to replace them all, after the black hole of money fills in a bit.

    That means all I have left to do is put in a bunch more fuses. I am going to double up and do them on positive and negative as a nice little safety extra.

    Do I need to load it and charge it for a few days, or will it probably be okay as it is?

  9. #9
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    Do not install fuses on the negative side. It will serve no purpose!
    Rich
    WWW.solarsaves.net

    NABCEP certified Technical Sales Professional

    http://www.solarpaneltalk.com/showth...Battery-Design

    http://www.calculator.net/voltage-drop-calculator.html (Voltage drop Calculator among others)

    www.gaisma.com

  10. #10
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    Quote Originally Posted by Crumb View Post
    At least they make 5000W panels. I never heard of an M2 but I assume it's military? Gotta be big ones. Have fun with those man! Serious hardware right there.
    Sunking stated it correctly -

    Most people in the world (except for backwards a few places that still use the English system) would realize that m2 mean meter square.

    Something like 10.37 square feet in one square meter.

    When will the idiot politicians have enough nerve to force the change to metric? The old system is worse than silly and anyone doing international work HAS to use metric.

    No one makes a 5000 watt panel for sale.

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