Solar Panel Wiring

Discussion in 'The Beginner' started by oldflemo, Apr 27, 2015.

  1. oldflemo

    oldflemo Funster

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    Just about to order a Solar kit which amounts only to a single panel,controller ,inverter and a MC4 connector
    My question is a simple one I think but that could be my senility kicking in!

    Do I really need a joint in the 6 mm solar panel cable to the controller as the length is less than 2 metres?
    Look forward to your advice.
    Thanks Ian
     
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  2. peterc10

    peterc10 Funster

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    If you are only using one panel it depends how long the leads fitted to it are. From memory mine were about 1m long, but you can get them fitted with longer or shorter ones.
     
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  3. tonka

    tonka Funster Life Member

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    As above, a lot could depend on how much cable is on the solar panel. Most do only have a short piece....
    On past jobs I have cut off the MC4, passing the original cable through the roof gland and then used a connection block once inside to extend the cable down to the controller. Every job is different and will depend on where you are siteing everything.
     
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  4. tonyidle

    tonyidle Funster

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    You do need a convenient method of disconnecting the panel. Most controllers don't like being disconnected from the battery when the panel is still connected.
     
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  5. Lenny HB

    Lenny HB Funster

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    2m sounds a short run, where are you monting the regulator?
    The regulator needs to be as close to the battery as possible, size of cable depends on the size of panel, length of run and what loses you are prepared to accept. For a 2m run even 4mm sq cable would be well over the top.
     
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  6. oldflemo

    oldflemo Funster

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    Thank you I didn't know that
    Ian
     
  7. oldflemo

    oldflemo Funster

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    Regulator is being mounted about 3 feet off floor behind drivers seat with the leisure batteries on floor immediately below it
    Ian
     
  8. gillnphil

    gillnphil Funster

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    I would not be too concerned about "loss" due to longer cables, its miniscule. Use thick cables to the controller, and to the battery. My cables are the orange ones like on a lawn mower, and are about 5 mtrs long. Batteries are always fully charged even in the winter.
    Phil
     
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  9. Voyger1010

    Voyger1010 Funster

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    answer No you don't especially if it's 6mm, as for needing to disconnect the controller had mine for 3 years on last van, never disconnected it once "why would you unless you had a major problem with it" Lots of technical advice on Google if you want to convince yourself. happy motor-homing.
     
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  10. Lenny HB

    Lenny HB Funster

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    I have 2 x 100 watt panels with a 5 m cable run, I used 4mm cable when panels are producing their max in high summer the loss amounts to 5%, 9.5 amps of a possible 10 amps, in winter panels are only producing a couple of amps loss is only 2% I can live with losing 80ma.
     
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  11. peterc10

    peterc10 Funster

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    The problem comes when you disconnect the solar regulator from the battery(ies) as Tonyidle stated. You would need to do that if, for example, you wanted to work on the 12V system or if you wanted to replace the battery. I have a Schaudt Electroblok and solar regulator and the instructions are clear that the load to the regulator from the panels must be off before you disconnect the batteries. I have solved it by fitting an in-line fuse on the positive feed just before the regulator and it is then a simple job of pulling the fuse.
     
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  12. oldflemo

    oldflemo Funster

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    Thank you for this really helpful and informative response
    Ian
     
  13. Voyger1010

    Voyger1010 Funster

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  14. Voyger1010

    Voyger1010 Funster

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    Absolutely correct, but some people choose to install a fuse to the -ve cable or a blocking diode to prevent overnight discharge, but with most modern controllers, this is not entirely necessary. In addition you could always cover the panels with a blanket to make sure they don't see the daylight, lots of different ways to work on the 12v system if you need to, without needing a joint in the cable.
     
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  15. oldflemo

    oldflemo Funster

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  16. Lenny HB

    Lenny HB Funster

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    If you have MC4 connector on the roof it makes it easy to add another panel plus most panels come with MC4 connectors anyway.
     
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  17. tonyidle

    tonyidle Funster

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    Perhaps if you needed to replace the leisure battery?
     
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  18. Lenny HB

    Lenny HB Funster

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    Although my panel is fused via the Elektroblock I always fit a fuse in line before the regulator, then I can just pull the fuse to disconnect the panel when working on the electrics.
     
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