Fitting solar from scratch

Discussion in 'Mech Tech' started by 1973daisey, Jun 22, 2017.

  1. I had second thoughts on that. Since I use the pop top quite a lot, I'll have to start parking "the correct way around" (I might invest in a compass ;)) otherwise my panel will always be shaded.
    In this situation the option to angulate will probably be useful.
  2. Love a solar panel thread.

    CollyP, Lord Congi and scrooge95 like this.
  3. theBusmonkey

    theBusmonkey Sponsor

    Blast from the past!
    Haven't seen you for a while fella, all OK I assume?
    Still waiting to see those road trip pics haha...
    PaddyD likes this.
  4. I'm good, how about you sir? I'll pop a few pictures up on another thread. Bus due in for some light restoration at the end of the year then redoing the solar setup.
    theBusmonkey likes this.
  5. mikedjames

    mikedjames Supporter

    It looks like I might have got hold of a couple of 100 watt flexible panels with corrosion damage (rotted tags). I may be joining the solar club..
  6. WHat happens if you on mains hook up at the same time with a trickle charger feeding into the battery at the same time as the solar ?
  7. the solar controller recognises that battery has enough charge and doesnt give anything to the battery
    Lasty, agaric and theBusmonkey like this.
  8. Thanks ! That also answer my doubts about running a split charging relay and a solar panel
  9. paulcalf

    paulcalf Supporter

    good news, as id like to see how it works getting the wire through on the devon concertina roof!
  10. same as above with a split charge
    agaric likes this.
  11. Quick question to those who have the mppt controller. Would it fit flush in the spare wheel well in the boot. My storage under the bench seat is becoming increasingly full.

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  12. probably, they arent that big, would have to go on its side though.
  13. Thanks @pkrboo

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  14. scrooge95

    scrooge95 Shadow chancellor of the exchequer

    On the subject of the MPPT controller, do they get warm / hot when the battery is up to full charge and the sun is still out - dissipating the unneeded energy as heat? And if so, would the controller need to be sited somewhere with air movement? A bit like @Fil6, when I get around to going solar (fingers crossed for Techenders next April after doing my research at this Sepember one!) I'm a little short on options for positioning the controller, and was wondering about in the wardrobe. Any thoughts? Am I going to turn my wardrobe into an airing cupboard?? :)
    womball, 1973daisey and Fil6 like this.
  15. Good point ☝️

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  16. theBusmonkey

    theBusmonkey Sponsor

    They do have heat sinks but TBH you'll rarely be able to feel even a little warmth as the situation you describe rarely happens in practice.
    They don't have to handle continuous high current in the same way as say a Ctek has to because the sun generally comes & goes.
    Ours is on the rear of the Westy style side cabinet and Zed actually installed the same type of controller in his engine bay. Our 20amp contrioller got a bit warm for the few months we spent in the Greek sunshine but was never a cause for concern:thumbsup:
    The battery charger gets warmer TBH.
    IIRC Matt (@pkrboo ) has his controller in the wardrobe.
    As with any 'leccy instal, so long as you're sensible with wiring (in terms of fuse protection and routing to avoid chaffing etc) you'll have no issues...:D
    Last edited: Aug 18, 2017
    scrooge95 and Fil6 like this.
  17. Just joined the solar panel club!

    2 100W rigid panels. One on the roof rack and the other one on an extension lead to be placed in the sun if the van is parked in the shade. :)

    The setup is still on its version 0 and will need to be improved (probably at techender) but it's working for our holidays in France!

    Thanks @1973daisey for the very informative thread!
    Last edited: Aug 19, 2017
  18. mikedjames

    mikedjames Supporter

    Its only some of the older controllers that used 'linear' regulators that have to get hot to drop voltage to the battery voltage from the solar cell and waste power.
    A 100 watt panel delivers 5 amps at 20v say. A battery at 12 volts means the charger might have to dissipate 40 watts if it acts as a resistor, and only deliver 60 watts to the battery on a very sunny day.

    A modern switchmode converter changes the 20 volts at 5 amps to 12 volts at a bit less than 8.3 amps by storing energy in a coil fed from 20 volts and releasing it into the battery at 12 volts. It should only be generating maybe 10 watts of heat in the process.

    A cheap Chinese solution to the problem with an MPPT label may still creatively dissipate 40 watts in a linear regulator as this reduces the bill of materials substantially. A couple of transistors on a bit of aluminium sheet, some resistors and a voltage regulator diode is cheaper than a microprocessor equipped switchmode power supply.

    The modern MPPT controllers should be hottest when transferring max power and cool down for other situations.
    And depending on the settings on the solar charge controller and the hookup charger, its a bit of a toss-up as to which one ends up charging the battery last on a sunny day.
    SeanOC likes this.
  19. mikedjames

    mikedjames Supporter

    Well, I have the solar cells, one of them has a rotted tag where its time at sea has killed it, but I can poke around in the greenery and hit metal, so a bit of time with a Stanley knife and some soldering will fix that.
    When they were new they were really nice state of the art semi-flexible panels, so not too big for 100 watts, I think the two will fit side by side on the poptop in front of the air vent panel.
    Now to work out the best way to mount semi-flexible panels on the pop-top without making holes in the roof - except maybe the air vent panel (as that is covered with an aluminum sheet by a PO - and so they dont blow off or get removed...
    and then run wiring down to a regulator.
    scrooge95 likes this.
  20. CollyP

    CollyP Moderator

    Could I respectfully request that no solar work at TE commences before 15.30. Thanks ;)
    Lord Congi, scrooge95, Lasty and 3 others like this.

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