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  1. #1
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    Default NL Weekender with 90W solar panel & controller ONLY ?

    I am not sure if this exact question has been sked before or not.

    However, here goes:

    With our new setup we no longer have 2x 105 AH deep cycle batteries in the rig or in the bakkie.
    Now towing a small caravan without alternator charging to the van - no big batteries, only a well used 70 AH starter type battery which seems to hold the fort for an hour or two.
    The idea behind this is how to keep the NL running while towing.

    At a campsite we can charge from 220v when available using either a 12 amp or a 7 amp pulse charger, but would then run the fridge off the 220 v supply.

    The QUESTON is:


    To what extent could we rely on a 90 W solar panel with controller to run the fridge during daylight hours (not through the battery - directly via the controller) ?

    The idea being to keep the fridge cool while towing with that small battery and then during the day using the panel only (assuming enough sunlight obviously)
    We have a good quality cooler box which can help using ice packs ... to bridge the gaps.

    What I am really asking is could we manage (say) a two or three night stay-over in a place without mains 220 v power ?

    Obviously if it is raining / overcast ... well, ja.
    But under sunny conditions with only moderate shade if any.

    Any and all comments appreciated.

    Maybe I am dreaming.
    Peter Hutchison
    Answering the call of the wild is just so much beter than answering the telephone.
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  2. #2
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    Default Re: NL Weekender with 90W solar panel & controller ONLY ?

    Pete We dont cool when we drive but for 3 or more day stay overs we will be using our 240 W Flexopower Mojave Gen II Panels plugged into the trailer direct where we have 2 x 105 A/H Deep Cycle Batteries that run our LED lights and 90 litre NL Fridge Freezer in the Trailer @minus 18 when we stop >> They arrived today and will be replacing our old heavy 160W Glass set up which is old now
    Last edited by Peter Betts; 2021/10/13 at 03:56 PM.

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  4. #3
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    Default Re: NL Weekender with 90W solar panel & controller ONLY ?

    You'll have to have a battery in the mix.
    Yes some solar controllers have a load output on which you can connect a fridge directly.
    The kicker is that a solar controller, all those I've ever seen anyway, needs to be connected to a battery to even switch on. Even if connected to the load output of a controller, on fridge start up for example where the fridge pulls a lot of current, it will lone some current from the battery since a 90W panel will only be able to supply 5A or so.

    If I understand correctly you still have a 70 Ah aux battery which is a high cycle which you will have the fridge connected to while driving. Just keep the fridge connected to it when you reach your destination and connect the solar to it.
    "The man who does not read has no advantage over the man who cannot read" - Not Mark Twain

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  6. #4
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    Default Re: NL Weekender with 90W solar panel & controller ONLY ?

    My suggestion would be a bit different. I will ensure the 70Ah is fully charged when leaving the home. Connect the fridge in a BH or Hella socket but not a unreliable sigarette lighter socket on the towing vehicle while en route. This leaves the battery to run the fridge while setting up camp and getting the panel in place. This is where no 220V.
    Keep the fridge connected to the battery as well as solar during the day. One does not want to try and run the fridge only on solar and also having the compressor to fail to run in the morning, late afternoon or when a cloud comes over.

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  8. #5
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    Default Re: NL Weekender with 90W solar panel & controller ONLY ?

    Yes I will use the old battery in the interim.
    When it fails (tick tok) then I will get a larger one but most likely still starter type due to quick re-charge ability mainly (and cheaper to buy).
    My main question has sort of been answered I think, which was "Can I run the fridge directly off the solar panel controller ?".
    It seems not, although, yes, there is a connection provided for direct to fridge (load).
    This confirms what I thought.
    Thanks all.
    Peter Hutchison
    Answering the call of the wild is just so much beter than answering the telephone.
    [B][SIZE=2][FONT=Calibri][SIZE=2][B]ISUZU KB 280 DT LE
    Modified Glider Hunter trailer fitted with RTT.
    Platkar = Chevy Spark 1.2

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  10. #6
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    Default Re: NL Weekender with 90W solar panel & controller ONLY ?

    The nice thing about the load circuit it will use battery power to add to solar during the fridge starting current. It also aids in cutting the load when the battery is too deeply discharged.
    There is a negative as some controllers cut the load if they sense a drop in voltage when the load is connected. Something one MUST check before the time.

  11. #7
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    Default Re: NL Weekender with 90W solar panel & controller ONLY ?

    Quote Originally Posted by Peter1949 View Post
    The QUESTON is:
    To what extent could we rely on a 90 W solar panel with controller to run the fridge during daylight hours (not through the battery - directly via the controller) ?
    Assuming the fridge draws about 2.7 amps when running. The 90 watt panel will provide max about 5 amps (PWM charger) .

    We recently seen that in clear sky the controller (mppt) only provides max 73% of a panel for a part of the day, so I think you would be lucky to get 4-5 hours out of the panel, assuming the fridge will be able to start with the amps available.
    Last edited by JLK; 2021/10/14 at 08:18 PM.
    Johan Kriel

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  13. #8
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    Exclamation Re: NL Weekender with 90W solar panel & controller ONLY ?

    Quote Originally Posted by JLK View Post
    Assuming the fridge draws about 2.7 amps when running. The 90 watt panel will provide max about 5 amps (PWM charger) .

    We recently seen that in clear sky the controller (mppt) only provides max 73% of a panel for a part of the day, so I think you would be lucky to get 4-5 hours out of the panel, assuming the fridge will be able to start with the amps available.
    This clearly shows why one needs the battery. If that panel gives out 5A and fridge uses 2.7A when running part of the 2.3A max available could be stored in the battery. Also when the fridge compressor stops more can go into the battery for using outside the 4-5 hours sweet spot.
    My 2 PWM controllers will not switch on to even provide power to the load circuit. It makes sense that the controller gets own power from the battery to operate. If it had to work from PV for own power it will not have power to do any settings or drive the display after sunset.
    Last edited by ekkekan; 2021/10/16 at 02:02 PM.

  14. #9
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    Default Re: NL Weekender with 90W solar panel & controller ONLY ?

    Quote Originally Posted by ekkekan View Post
    The nice thing about the load circuit it will use battery power to add to solar during the fridge starting current. It also aids in cutting the load when the battery is too deeply discharged.
    There is a negative as some controllers cut the load if they sense a drop in voltage when the load is connected. Something one MUST check before the time.

    Personally I never use the load output on solar controllers, I connect directly to the battery, many anyway have a limited output rating which doesn't make them suitable for a fridge for example.
    I guess it has its place and its uses, but as said I don't bother.
    "The man who does not read has no advantage over the man who cannot read" - Not Mark Twain

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