Help with my 300w Mppt solar system install.

Discussion in 'Tech/Mech General' started by Plinky, Feb 1, 2016.

  1. Plinky

    Plinky Funster

    Joined:
    Dec 21, 2015
    Messages:
    30
    Likes Received:
    5
    Location:
    UK
    Hi,

    I'm new to motorhoming and this forum, but after a few 'life changing events' I recently bought a Westfalia James Cook (2004) with a view to travelling for months on end to nice places. I intend to wild camp quite a lot and have the potential power wise to stay in one place for a few weeks at a time. I had a 100w panel fitted to the roof when i bought it and went away for a couple of months. I soon realised that after wild camping for a few days in the same spot it would not be anywhere near enough wattage for my needs. With my condensor fridge on and charging laptops etc, my batteries went down everyday, and after 3 days or so, I had to drive off to re-charge them. So, on my return, I did some roof space calculations, and bought 3 x 100w semi-flexi panels, which is the maximum i can get to fit on my roof. I also purchased the mppt controller i saw recommended on this forum, the 25a MPPSolar PCM 3012. I have done a lot of reading on this forum, and intend copying one of forum member 'Techno's system installs i read about (Many thanks to him, its really helped me a lot reading his posts on solar). That system had a fuse between the panels and the controller (just so i can turn power off quickly if needed) and between the controller and battery's, (two 85ah gel type already fitted to van.) My first question is whether i should wire in parallel or series. I'm still a little confused about what is best for my set-up and wild camping plans. Secondly, I'm not sure what fuse sizes i need either side of the controller? Finally, and again copying the previously mentioned forum member :), i'm intending to fit a 12v cigarette lighter type socket to the controller load terminals so i can charge things during the day. Is that a good idea with my set-up, or are there some down sides to using it for that? I show details of my panels below. Thanks for any help. Screen Shot 2016-02-01 at 15.00.17.png
     
    Last edited: Feb 1, 2016
  2. SomeoneElse

    SomeoneElse Funster

    Joined:
    Apr 22, 2013
    Messages:
    571
    Likes Received:
    375
    Location:
    Cotswolds
    Fuses: You say the one between controller and panel is for isolation a fuse is not needed for protection so don't one too close to the actual max current as it might blow and be a nuisance. Max current is 3 x 6.02 amps. I'll opt for 25 or 30A.
    The one between battery and controller should be near the battery to protect the battery should the cable short to earth. Sizewise the max output of the controller is 25A, I'll go with 30A for this.

    The MPPT range of the controller is 15 to 37V, so two panels could be in series, but with three panels you have no option but to put them in parallel.
     
  3. Boringfrog

    Boringfrog Funster

    Joined:
    Jul 13, 2008
    Messages:
    974
    Likes Received:
    443
    Wire batteries in parallel.
     
  4. Augusta08

    Augusta08

    Joined:
    Aug 25, 2015
    Messages:
    59
    Likes Received:
    36
    Location:
    Morbihan
    Assuming normal 12v panels with diode discharge protection (the norm) wire panels in parallel also. That way if one panel is shaded the others still give out their maximum available power.
     
  5. andy63

    andy63 Funster

    Joined:
    Jan 19, 2014
    Messages:
    1,844
    Likes Received:
    6,411
    Location:
    south shields
    Hi.. series or parallel will depend on your controller and whether it can handle the max voltage in series.. had a quick look and you will be on or over the controler max voltage of 50v with 3 panels in series.. think I was looking at the right specs.
    Think techno did some tests on the two configuration and there wasn't much in it... your controler will definitely handle the max current in parallel....
    A 25 amp fuse should be fine looking at your system... not sure you need one in the input side... I didn't fit one there as I thought my controler had the built in protection...but since then I've read most do...
    The load terminals on the controller draw from the battery and not direct from the panels..to power lights at night etc...
    As long as what's connected doesn't exceed the max load allowed can't see a problem with connecting whatever suits..
    Ta andy.
     
  6. Plinky

    Plinky Funster

    Joined:
    Dec 21, 2015
    Messages:
    30
    Likes Received:
    5
    Location:
    UK
    Wow, these are the quickest responces I've ever had on a forum. Many thanks they have answered my questions, and will enable me to get on with ordering final parts. As an aside, i had a terribe job getting off the old panel. They used so much sikaflex that the panel was ruined removing it. ( maybe i did it wrong). I ended up using 'sticky stuff' solvent and an old sharpened credit card together with a similar sized but thicker 'ice scraper' from Halfords. It took a long time ! I opted for semi-flexible panels again, but found clamps on ebay which I can highly recommend. Much less glue overall, and panels are unboltable for any future eventualities. The first pic below shows the sikaflex left behind by the old panel, and the second, two of my new panels fixed using these clamps...My third panel will go in front of the large Heki roof window.

    http://www.ebay.co.uk/itm/NEW-6-x-C...201858?hash=item3d1085b002:g:JiEAAOSweW5VYj1Y

    Cheers. IMG_2751.jpg IMG_2753.jpg
     
    Last edited: Feb 1, 2016
  7. BusyBuilder

    BusyBuilder Funster

    Joined:
    Jan 31, 2016
    Messages:
    162
    Likes Received:
    89
    Location:
    Cromarty
    • Informative Informative x 1
Loading...

Share This Page