Solar Panel...Max Current and maintenance

Discussion in 'Motorhome Chat' started by zen navigator, May 21, 2010.

  1. zen navigator

    zen navigator Read Only Funster

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    Had my Benimar Europe a couple of months and first time with Solar Panel. Now I have it, how did I ever live without it :Smile:

    On my panel there is a 3A fuse which is for the charging system(i think, fairly sure) Which I think is low?

    My main question is what is the rating on the Solar Panel I presume is it a standard on the Europe 6000 ST so a fellow Benimar owner may know.

    The solar panel size is approx 3 1/2 ft to 1 1/2 ft this is a guestimation. I usually get 2.5A on a sunny spring day. But last week it went over the 3A not for long but it was there. So thats why I question the 3A fuse rating.

    Looking around it seems it is either a 60W or 80W. If 60W I guess that ties in with the 3A thing as I believe these deliver 17V(Also that seems suprisely high!)

    But if 80W, in summer I should be expecting more Amps. But then we got back to this 3A fuse thing.

    One additional query are there cleaning products that will improve the performance of the solar panels or just a wipe will do. Notice mine has a thin layer of grime. Does this significantly effect the performance of the Panel. I guess keeping it clean will only help :Wink:

    Any thoughts

    Dave
     
  2. Douglas

    Douglas Read Only Funster

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    HI Dave,

    To calculate the amperage you divide the wattage by the voltage IE 80/12 = 6.5 amps.

    This is not exact but near enough.

    No the full capacity of the panel is only reached if the panel is pointing directly at the sun at all time, so that = %100

    if the panel is tilted up to face the sun but not rotated the you loose about 33%

    If the panel is laid flat the you loose about 66%

    So on a 80 watt panel .

    Follow the sun you get 6.5 amp
    Tilted to the sun you get 4.2 amp
    with a flat panel you get 2.1 amp.

    These figures are not exact but give you a near estimate of what is happening.

    The charging voltage from the panel has to be higher that the battery's and this is normal, IE you cant charge a 12 volt battery on 12 volt if that's what you are thinking.
    Good luck Doug...
     
  3. Dodgey

    Dodgey Funster

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    The 3 amp fuse could relate to the wiring from the panel to the controller or the controller rating. It could be someones had the fuse blow and put the wrong one in, gone lower for safety. You'd need to review the wiring and controller though.


    Cleaning, I just give our a gentle wash now and again, nothing special.
     
  4. Reallyretired

    Reallyretired Funster

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    Detroit Solar suggested ordinary car wash/wax. Put it on and let the rain wash it off, presumably the wax stops the grime sticking.:thumb:
     
  5. zen navigator

    zen navigator Read Only Funster

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    Thanks for the replyies Guys.

    I will have to have to review the wiring and at install IDM alarm. The issue is just more than Solar Panel charging current, as there as been some modification of the auto battery changeover as well.

    The system works, but its kinda of orthodox i.e the habitation area uses both leisure and vehicle batteries as a kinda dual setup.
     
  6. zen navigator

    zen navigator Read Only Funster

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    Hi Doug

    Thanks for the lesson in Ohms Law, but I've got that covered :Wink: , and I was not so much questioning why the voltage is greater than 12v but why 17v as oppose to a 14.4v charging voltage you get from you vehicle charging system i.e why is significantly higher?


    Interesting stats on the efficiency of flat based solar panels. Your stats would support what I am seeing i.e avg 2A over the day based on a 80w panel.

    But I am thinking mine is a 60w panel and someone has told me the panel is 55w on a Benimar. Which does translate to the max 3A at 17v. Which means the efficiency is much better than you detail i.e @ 66% efficency?

     
  7. Robinhood

    Robinhood Read Only Funster

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    You are (probably) measuring the output from the panel direct. 17v is about standard from the size of panel we are talking about.

    This type of voltage should always go through a solar controller/regulator to the electrical system.

    On the Benimar, as standard, that output goes into the back of the control panel, which contains a solar charge controller, which will both reduce the voltage applied to the battery to the standard charging voltage (say between 13.8 and 14.5v) and also ensure there is no overcharge.

    This component failed on mine, resulting in no charge. (and I proved it was the control panel by removing it, unclipping the solar feed, and measuring the 17v there).

    I'm still wondering what the panel wattage was on mine; I have an old brochure downloaded here, but unfortunately it doesn't go into enough detail :Sad:.
     
  8. Douglas

    Douglas Read Only Funster

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    OK, I will see if I can help.

    If you are charging a battery that has reached a part charge, then you always need a greater voltage to take it any higher IE you can not charge a battery at the voltage that is the same as the battery to refer back to my first post, you can not charge a battery at 12 volt with 12 volt also you can not charge a battery at 14.4 with a 14.4 voltage,

    The charging voltage is always greater than the battery voltage. As to the panel voltage being 17 volts, (and here you prove it to yourself) try measuring the voltage from a battery charger with no form of control on it, IE. a cheapo that you may have in your garage. You will find that the voltage from the charger is a lot higher that 17 volts.

    The 66% was not efficient but 66% loss. also you quote "3A at 17v." this can not be so, as the current drawn increases the voltage drops, try putting an ammeter direct across the panel when it is disconnected from the battery, you will find that the voltage goes to zero and the amperage goes to the max the panel can generate, and don't worry this will do no harm to the panel.

    I hope this helps

    Doug...
     
  9. zen navigator

    zen navigator Read Only Funster

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    Thanks for advice Doug.

    The bottom line is it is doing what it says on the tin. If it aint broken and all that....but its nice to understand what is going on in the event of a malfunction.

    I going to be wheeling my MH into my local automotive electrian, as I have other electrical issues(not show-stoppers, but niggling).

    Dave

     
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