Solar System Upgrade

Discussion in 'Motorhome Chat' started by mr maz, Jun 29, 2016.

  1. mr maz

    mr maz Funster

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    Thanks to advice received from other "Funsters" we have recently upgraded the solar system on our van. Considering how dull the weather has been so far this summer we have been impressed by how much more efficient the system is now.:)

    We thought other might benefit from an account of how we did it.

    Firstly I replaced the dealer installed regulator with one recommended by @Techno, MPP SOLAR PCM-3012. The old regulator never brought the batteries above 13.6v on bulk charge and 13.1v floating, the new one to 14.3v and 13.4v Also I upgraded the cabling to the battery to 4mm2. The final addition inside the van was to instal a Sterling "Auxiliary Battery-Battery Charger/Maintainer" to keep the engine battery charged. This I can't remember who recommended.

    Next, on the roof, I added a 100 watt panel to augment the existing 2x 85 watt panels that the dealer had instaled. I added a blocking diode to the new panel and a diode into the feed from the original panels. 4mm2 cable was used to the regulator from the new panel and from the diode added to the orginal panels. The dealer had glued and screwed the 85 watt panels to the roof (using zinc coated steel wood screws that had rusted,:eek: I replaced them with S/S self tapping screws and plenty of sealant). I decided to leave the original panels well alone as their output voltages and currents were within spec.

    The upshot being that today, even in the rain, we were often getting up to 2.5 amps charging current. (y)Thanks again to all "Funster" who gave advice.
     
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  2. Bacchus

    Bacchus Funster

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    LoL - I could hardly contain my excitement when I saw the heading, I realised as I was waiting for it to open that you didn't mean the solar system...

    Probably doesn't help that I am just in the middle of a windows 10 upgrade on another PC...

    Interesting though, and thanks for posting, I would love to see some feedback from the return you get in winter months
     
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  3. Terry and Jan

    Terry and Jan Funster

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    Well done mate.
     
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  4. andy63

    andy63 Funster

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    Hi.. I've been trying to get my head round mixing panels of different wattage. .. I was under the impression that unless the panels have the same voltage rating if connected in parallel, or current if connected in series then the overall available power would be reduced..
    So my question is how exactly have you added the 100w panel and how are the two 85w wired..ie series or parallel. .
    Are the diodes you installed in addition to existing diodes on the back of the panels... assuming there are ...but all the panels I've seen had diodes in a little box on the back...
    Sorry if sounds like an interrogation lol... but these things interest me
    Ta andy
     
  5. Techno

    Techno Funster Life Member

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    My last van had 100+60+40+40 . No problems
    Parallel is the only way, it doesn't matter what each one outputs as long as they're all for 12 volt system or roughly 21.5 volts open circuit
     
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  6. Techno

    Techno Funster Life Member

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    Nice robust unit which makes the £54 easier to accept
    [​IMG]
     
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  7. Techno

    Techno Funster Life Member

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    There may be a minute drop in mppt efficieny if the max output voltage of each is slightly different but it will be repeat minute
     
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  8. andy63

    andy63 Funster

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    Cheers Andy. .. was aware that folk did it but the reading I had done made me think the system output would be reduced..
    What would be the purpose of the diodes mentioned in Mr maz post.. I thought panels had blocking diodes installed...
    Andy
     
  9. Techno

    Techno Funster Life Member

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    I haven't fitted any, I only use panels that have twin diodes and the panel cells wired as two halves to reduce shading effect
    [​IMG]
     
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  10. mr maz

    mr maz Funster

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    Hi @andy63
    Our 3 panels are all connected in parallel and designed for 12 volt systems. Normally the diodes within the panel junction box are what I think are called balancing diode and are required because the panels have 36 cells. Blocking diodes are to stop sunlit panels discharging through any other panel should one become shaded. The regulator, as well as regulating the supply to the batteries, also stops the batteries discharging through the panels at night.
     
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  11. andy63

    andy63 Funster

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    Thanks.. I'm getting confused... blocking diodes are just that and prevent battery discharge through the panel...
    Bypass diodes are to allow a system to operate in the event of a panel becoming shaded,or if a panel has a large number of cells they install bypass diodes between the banks to lessen the effect of shade...
    So are the diodes on most panels blocking or bypass... sorry again for all these questions ...:)
     
  12. Techno

    Techno Funster Life Member

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    The only other I know who fits extra diodes is Peter Forbes. If I cover one of three panels I only lose a third of the output and certainly don't lose energy back into the covered unit.
     
  13. vwalan

    vwalan Funster

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    cant find the right info but my bp solar panels have diodes already on them built in to the box on the back . i,m sure most have them . even my old intersolar that are about 16 yr old came with them as standard .
     
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  14. Techno

    Techno Funster Life Member

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    The diodes in panels are blocking diodes. Bypass diodes are only needed where panels are connected in series
     
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  15. andy63

    andy63 Funster

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    I thought they may install bypass diodes on large panels between banks of cells to lessen shade effect..
    Thanks for the replies and sorry @mr maz for hijacking your thread ..:)
     

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  16. Techno

    Techno Funster Life Member

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    Yes that is correct Andy having re read but you only need bypass diodes between panels if they are in series.
    The regulator has a blocking diode to prevent a return path
     
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  17. pappajohn

    pappajohn Funster Life Member

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    Thought for a moment professor Brian Cox had changed something in the universe. :whistle:
     
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  18. vwalan

    vwalan Funster

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    mind the best panels are those luna panels that you can get . if my memory is right jim had some info a few years ago . luckily we bought the converter diodes and got luna panels working with our solar panels thanks jim.
     
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  19. Steve

    Steve Funster Life Member

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    Usefull upgrade Mr Maz with the price of the bits now its a good time to go as far as you can with panels and batteries.(y)
     
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  20. pappajohn

    pappajohn Funster Life Member

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    No good Al....they only work during a full moon with no cloud.
     
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