Solar Connection Q

Discussion in 'Solar Power' started by Kool Kroozer, Feb 12, 2016.

  1. Kool Kroozer

    Kool Kroozer Funster

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    Have got panels and all the bits on order and waiting for delivery, the set up i have ordered is x2 140w panels, solar charger/controller thingy with the cable, brackets etc etc Oh and 2 new 120ah Leisure batteries - and its this bit (battery connection) thats puzzling me as i have seen different ways its set up... the 2 new batteries - positive/positive - negative/negative, Now the leads that were originally just on one battery that supplies the hab power - do they just connect to one battery or do i have to connect positive to one battery and negative to the other battery ?
    And the same with the Solar cable coming out from the charger too - both leads to one battery or split one on each ?
    many thanks in advance - KK
     
  2. Geo

    Geo Trader - Funster

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    Batteries_In_Parallel.jpg It matters not,you are just making one big 12v battery that happens to have 2 x poss and 2 x neg poles, use which ever is convenient, No need for the expense of longer cables if the two originals will reach one of the batteries
    I do it like this and it matters not which poss and neg the power is taken from or which poss and neg the charge goes to, after all its just one battery(y)
    Geo
     
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  3. Kool Kroozer

    Kool Kroozer Funster

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    Thanks for the reply, is this the same for the solar cables too ?
     
  4. Geo

    Geo Trader - Funster

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    Yes it makes no difference
    Only tip is to make your solar cable runs as short and direct as possible
     
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  5. Kool Kroozer

    Kool Kroozer Funster

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    Many Thanks G (y)
     
  6. John Laidler

    John Laidler Funster

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    And how are you going to connect your panels, series or parallel? I'm doing mine in series but I know others have done parallel. Worth checking if the instructions with the solar controller have a recommendation.
     
  7. Kool Kroozer

    Kool Kroozer Funster

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    didnt even give that bit a thought (head scratchin time)
     
  8. Stealaway

    Stealaway Funster

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    Your panels will probably be around 20V each, check your controller for specifications.
    I would wire them in parallel.
     
  9. Kool Kroozer

    Kool Kroozer Funster

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    yes stealaway, panels are 21v each and the controller is a 20amp (was told it will be ok if ever i need to add more panels - BTW connecting in parallel is pos to pos neg to neg ?
     
  10. John Laidler

    John Laidler Funster

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    Theoretically, if you ever did get 140W out of each panel (which you won't unless you move to the equator and there is a small local star going supernova at the time) then wiring them in parallel will give you about 20 amps through the controller, so within the limit but no room for expansion - again in theory as most of the time they'll be producing a lot less current. There will also be a voltage limit for the controller, on mine it is 75 volts and only 15 amps, which is one of the reasons for wiring them in series. Even three panels could be used and the current will still remain under 15 amps.

    As a generalisation it is more efficient to use high voltage/low current to transmit electrical power, its what the National Grid do - or whatever they are called these days. The more amps you put down a wire the greater the losses due to heat. But the difference isn't great at the sort of currents and voltages we are talking about for solar charging - but every little helps. :)
     
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  11. Kool Kroozer

    Kool Kroozer Funster

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    Just an update on a queery, the solar controller i have is a 30amp and not a 20 as stated previously - question i need info for is this: I have read on here that its advisable to fit a in line fuse from solar to the controller and another from the controller to the leisure battery - correct ? if so what fuse rating do you fit on the above set up ?
     
  12. John Laidler

    John Laidler Funster

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    You might find the controller already has a fuse, my 15 amp controller has a 20 amp fuse but if not then I suggest in your case make it 30 assuming you are using decent thickness wiring, 6 square millimetre is usually used. This should be on the positive side going to the batteries.
    I'm not putting a fuse on the solar side as the panels can be short-circuited without harm and wouldn't blow a fuse anyway unless the rating was below the maximum current the panels can produce.
     
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