Solar Panels & Winter Sunshine?

Discussion in 'Motorhome Chat' started by StitchUp, Feb 22, 2014.

  1. StitchUp

    StitchUp Read Only Funster

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    At times today we enjoyed blue skies and bright sunshine.

    Should the solar panels produce the same voltage on a similarly bright sunny summer's day the only difference being, it's very warm?

    Today, my panels were producing just over 47v but in the summer I have seen 67v.

    Cheers
     
  2. Phill D

    Phill D

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    Sh*t ! how many panels you got for 67volts

    the brightness and the angle of the sun to the panel surface makes big differences.

    as most panels are flat on the roof in summer they get more direct sublight as the sun is higher in the sky..
     
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  3. aba

    aba

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    I think with that voltage he on about household grid tied panels :Rofl1:
     
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  4. pappajohn

    pappajohn Funster Life Member

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    i would be very concerned if i saw 47 volts from a solar panel.

    normal open circuit voltage from a 12v panel should be around 17v between the panel and controller.

    if you get much more than 14v continuosly on the controllers output you will fry. your batteries.


     
  5. pappajohn

    pappajohn Funster Life Member

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    Mmm...just seen Aba's reply. :Doh:
     
  6. lunarman

    lunarman Funster

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    I may be talking rubbish here and reading to much into the original post.

    The post says "panels" could they be connected in series rather than parallel would this produce greater voltage similar to connecting 2 batteries in series.

    Then 3 panels would produce 60+ volts in full sunlight.

    If I'm wrong blame the glass of red wine by the side of the keyboard. If I'm right then the installation needs to be checked to ensure they are correctly installed.

    Lunarman
     
  7. SomeoneElse

    SomeoneElse Funster

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    A 12volt (36 cell) panel will have an open circuit voltage of about 22.5 volts, and a max power voltage of about 17 volts.
    Two in series or a 24volt (72 cell) panel will give twice those readings.
    A good MPPT controller will cope with upto 100 volt open circuit voltage. It will operate the panels at max power voltage which should be similar, within a couple of volts, both summer and winter.

    If the panels are on a house connected to a grid tie controller I would not expect a big difference between summer and winter voltages. If on a MH I would expect them to be at max power voltage when charging the batteries rising to open circuit voltage when the batteries are fully charged.

    Gordon
     
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  8. StitchUp

    StitchUp Read Only Funster

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    I have 2 x 200 watt panels, they're connected in parallel.

    [​IMG]

    They feed a Tracer-4210RN MPPT Regulator with a maximum solar input voltage of 150VDC.

    I get approx 14.1v output to the battery - just about topped up in this picture.

    [​IMG]

    I'm gonna have to wait until the summer to check my facts!.

    I'm fitting a CBE battery controler tomorrow to charge the vehicle's starter battery when the leisure batteries are at capacity.
     
    Last edited: Feb 22, 2014
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  9. pappajohn

    pappajohn Funster Life Member

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    looks like those are 24 volt panels.....and the controller is dual input 12 or 24 volts
    a good 12v 200 watt panel will produce, on paper, around 16 amps...in reality maybe 10 to 12 amps...not the 5.5 amps in the spec.

    double up the voltage you reduce the amps by half.
     
    Last edited: Feb 22, 2014
  10. Moodybrook

    Moodybrook Funster

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    My 165W 24V panel this morning in the blinky Scottish sun was giving me 14.7 V and 5.4A. It never got like clear sunshine. When it went fully overcast before the rain came on proper and I was dragged away from my fixation I was still getting .5 to .8A Probably about enough
    to replace the stealth amps being stolen from my veh batts

    I contacted my supplier as I thought they had made a mistake sending a 24V panel but they explained that the Tracer MPPT controller was well equipped to rectify that to suit my 12V battery bank.

    Pippa John as I said I have gone with the alternative, Leisure to Veh batt solution, with a 12V mcb (alternative to a fuse). Well I did forget ! already ! :Doh: and wound the old elastic band up, the MCB did not trip, the end of the world did not come either :thumb:
     
  11. funflair

    funflair Funster Life Member

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    The 5.5 amp quoted is at 36.4 volts so that would be more like 16.5 amp at 12 volts from the regulator.

    Still not sure how he sees 67volts if they are connected in parallel.

    Martin
     
  12. pappajohn

    pappajohn Funster Life Member

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    what size MCB did you use and where did you source a 12v MCB ?

    It may be if the chassis battery was in top condition and fuly charged it may not have drawn a high current from the leisure battery or the linking wire was too thin and wouldnt allow a high current to pass.
    I wonder what the result would be if the chassis battery was less than fully charged when the engine was cranked
     
  13. Minxy Girl

    Minxy Girl Funster Life Member

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    I am now utterly confused! :Eeek:

    I didn't realise you could fit a 24v solar panel to a MH! :Blush:

    Can someone explain to me in plain English what difference this means in reality compared to a 12v panel in terms of usable output.

    I have a 75w 12v panel (Alden) ... would a 24v one give more power? Have I totally lost the plot ... probably! :RollEyes:
     
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  14. Moodybrook

    Moodybrook Funster

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    similar site to this, there is a 20A version mine is the Hong Kong babies. Took a fortnight, over Xmas to come.

    http://www.ebay.co.uk/bhp/12v-circuit-breaker

    Yes my batteries were probably at full charge, perhaps that is what saved the situation. This is of course is what I am hoping will always be the case and justify my panel ? :thumb:

    The cable I am using is 10mm squared, probably not thick enough over the 3.6M run but that is all I could get my hands on at the time.
     
    Last edited: Feb 22, 2014
  15. StitchUp

    StitchUp Read Only Funster

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    Forget the 67v for now, I might have been mistaken - have to wait until the summer sunshine to confirm :)
     
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  16. pappajohn

    pappajohn Funster Life Member

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    is it this type ?

    Your link just points to an ebay listing page, not an item.


    [​IMG]
     
  17. Moodybrook

    Moodybrook Funster

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    Yes that is the one, 20A £5.97 postage free.

    What do you reckon?

    I am making a hang on the steering wheel reminder, hopefully a fail safe move.
     
  18. pappajohn

    pappajohn Funster Life Member

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    been looking at those myself....thinking inverter fuses as i saw some rated between 100 and 300amps.

    Far cheaper than buying 100amp+ stereo amplifier fuses (as fitted by boy racers) and carriers from the likes of Halfrauds.
     
  19. funflair

    funflair Funster Life Member

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    Hi Minx

    12 volt of 24 volt does not really matter as long as the regulator can handle what goes in, the important bit is that you get 12 volts out for your MH system. No more power from 24 volts just look at the wattage of the panel that is the power W=VxA so more volts from panel is less amps but the watts come basically from the size of the panel.

    After saying all that just stick with a 12volt panel and you can't go wrong.

    Martin
     
  20. jenny and mitch

    jenny and mitch Funster

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    Solar panels in parallel

    OK fellas while you have your brains switched onto solar, a question.. We are having a 100w panel put on at the factory, can I, at a later date, fit another 100w panel in parallel to it ?? And would I have to run the cable from the additional one all the way to the regulator with its own wires, or could I splice into the cables of the factory fitted one before they enter the van ?? AND,, would that give me 200 watts at 12v and therefor a theoretical 16 amps ???
    I would appreciate an answer to what to you long time funsters must be a repetitive question.. Thanks in anticipation.. Mitch.
     
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