Adding more solar panels

Discussion in 'Motorhome Chat' started by UK Pete, Mar 19, 2015.

  1. UK Pete

    UK Pete Read Only Funster

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    I have been upgrading my whole power system gradually as and when i can afford to
    The first phase was change the two lesuire batteries for new and bigger capacity, then i upgraded the regulator to mppt capable of 300w , then today i have received two new 80w solar panels which i will fit saturday, making my total solar 280w
    My question is, rather than route new cabling into the van can i cut in to the wiring on the roof for my existing 120w solar panel , this will save me loads of hassle , i just want to be clear that it is ok to do it this way, and what sort of connectors do i need to order
     
  2. canopus

    canopus Funster Life Member

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    No need to cut into the cable. Make the connection within the terminal enclosure of the existing panel. Thats assuming that the cable from your existing panel to your batteries is man enough to carry the increased load.
     
  3. Techno

    Techno Funster Life Member

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    Yes cut and use MC4 connectors and two or three way splitters. Panel JB's don't have entry glands for more than the original cables. You will need a crimping tool , connectors are cheap.
     
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  4. Techno

    Techno Funster Life Member

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  5. eddievanbitz

    eddievanbitz Trader - Funster

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    What size is the original cable? Do you know?
     
  6. Techno

    Techno Funster Life Member

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    This was my centre of three panels prepared for the outer two
    [​IMG]
     
  7. eddievanbitz

    eddievanbitz Trader - Funster

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    LOL Andy, not you, the OP I knew that you would know (y)

    It is that some of the wire used by dealers and converters wouldn't be up to tying a chicken, let alone adding additional panels

    :eek:
     
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  8. Techno

    Techno Funster Life Member

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    I rightly or wrongly assumed that Pete had installed the 120 watt panel himself :)
     
  9. John Laidler

    John Laidler Funster

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    I may be missing something here but if you plan to link the panels in series, which is best I think if you have different sized panels, make sure your controller can take the maximum voltage of all the panels added together.
     
  10. Techno

    Techno Funster Life Member

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    No he plans to parallel them on the roof rather than in the van
     
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  11. UK Pete

    UK Pete Read Only Funster

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    The 3 panels will be in parallel, giving the mppt 280w and 12 volts . it is a 12v 25A 300w controller so just right for this parallel set up, i think i am right here?
    pete
     
  12. eddievanbitz

    eddievanbitz Trader - Funster

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    So long as the wire can handle 280 watts Did you install the cable originally? can you remember the spec? or did the dealer/manufacturer install the wire?

    If so, if you can find out, I or Andy (plus many others) will easily be able to tell you if it is man (or woman lol) enough

    Eddie
     
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  13. John Laidler

    John Laidler Funster

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    Again, I may be speaking out of my fundament, but if you have different sized panels in parallel is this the most efficient way of doing it as I thought the panels need an optimum voltage? Secondly, if you are connecting in parallel the wires going to the controller need to be a lot thicker than the originals probably were, ie, don't break into them on the roof. They need to be replaced.
     
    Last edited: Mar 19, 2015
  14. Techno

    Techno Funster Life Member

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    You cannot do THREE panels in series. The voltage will exceed the spec of the regulator by a long way.
     
  15. John Laidler

    John Laidler Funster

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    That was my understanding too. The question I guess is should you "bodge" the installation with mismatched panels or not? By which I don't for a moment criticise the OP, more a rhetorical question.
     
  16. Techno

    Techno Funster Life Member

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    Nothing wrong with different sized panels. Preferably having the same MPPV but not life or death.
     
  17. UK Pete

    UK Pete Read Only Funster

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    Wire size going to be 6mm, i will investigate the original size wire and upgrade if necessary
    pete
     
  18. Lenny HB

    Lenny HB Funster

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    6mm Should be fine, I only used 4mm on my 2 x 100w panels the cable run was only about 5 meters. Although there will be a few percent loss, the maximum loss will occur when the panels are producing their maximum output in high summer so not worth worrying about. In the winter when they are only producing a few amps the loss will be insignificant.
     
  19. Techno

    Techno Funster Life Member

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    6mm is the biggest that will fit MC4 connectors
     
  20. Pikeman

    Pikeman Funster

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    I wish I knew what you lot were talking about. I would love to fit solar to the van myself.
     
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