Dual solar controllers year or nay.

Discussion in 'Solar Power' started by friar tuck, Oct 13, 2016.

  1. friar tuck

    friar tuck Funster

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    Hi.ive just got a 2010 autotrail which has 2 solar panels.the mh was originally supplied with a single solar panel running through the sergeant control panel and charger as fitted standard.at some stage it has been fitted with a second solar panel and when I first got it it had a cheap and nasty controller on,I've since swapped this for an mppt which I bought through recommendations on here.
    My question is would it be better to rewire both through my 20amp mppt or leave as is.the inbuilt auto trail unit is only capable of controlling 100watt so they can't both be put through to that. I'm just thinking if 2 separate controllers are supplying charge to the same batteries will there be any conflict there?thanks in advance.
     
    Last edited: Oct 13, 2016
  2. tonyidle

    tonyidle Funster

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    Wire them both in parallel through the most controller. It's ideal, but not essential, if both panels are the same size. Either way the most controller will make better use of them than the cheapo. I run a 55W, an 80W, and a 95W, in parallel through an mppt controller very successfully.
     
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  3. John Laidler

    John Laidler Funster

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    Using two controllers is a good idea, it minimises the effect of shading on one panel. However, if I was doing it I would use matching controllers.
     
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  4. tonyidle

    tonyidle Funster

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    Fair point but shading isn't usually a big issue when roof mounted.
     
  5. andy63

    andy63 Funster

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    Hi John does having them in parallel (as opposed to series ) not minimise the shading effect on one panel anyway..??Ie you still get the benefit of one panel if one is patially shaded..
    Andy
     
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  6. Derbyshire wanderer

    Derbyshire wanderer Funster Life Member

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    I also have 2 X 100w panels and Sargent electrics which cannot handle more than 100w
    Both panels are wired in parallel to a mppt controller and direct to the leisure batteries. I have fitted a battery to battery charge controller that trickle charges the vehicle battery once the leisure voltage gets to 13.5volts.
    It's simple and foolproof as there is nothing to manually change over.
    I do have a cheap and cheerful meter connected that tells me the charge output and daily watt hours but the Sargent battery voltage indicator does just as good for telling me that all batteries are being charged
     
  7. tonyidle

    tonyidle Funster

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    Yes.
     
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  8. friar tuck

    friar tuck Funster

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    Derbyshire wanderer when you took the origonal feed out of the sergeant to put to your separate mppt how did you gain access to the cables?
     
  9. John Laidler

    John Laidler Funster

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    I believe it does which is why I've wired mine that way but I understand twin controllers is marginally better.
     
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  10. andy63

    andy63 Funster

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    While on the subject of shading... I was surprised how much effect it has.. not done any real tests but even a very small section of a panel in shade made a big difference to the output...
    I think Alan @rupert can confirm this... we were talking abut it and he ran a quick test and was surprised at the drop in output when he shaded a part of his panel.... no specific details I'm afraid...
    Back to the original post... I'm thinking most manufacturers would be better off either fitting a decent integrated solar controller of say up to 300w or not bothering...
    Mine has a max built in capacity of 120w I believe but no idea where or how to wire it in and the van came with no instructions on how to...
    I ignored it and installed 280w... independently. ..after checking on the forum first about problems.. fortunately none to date...
    Other than techno taking the water about the number of brackets I used to secure panels with :LOL:
    Andy.
     
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