Amperage for 4x 400W 12/14.4V system





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  1. #1
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    Default Amperage for 4x 400W 12/14.4V system

    Hello guys,

    This is a very straightforward answer in my opinion, using high-school physics, under IDEAL CONDITIONS:

    W=VA
    1600W = 14.4V (avg) x A
    A = 1600W / 14.4V = +-112A.

    This means for two Victron BlueSolar 100/50s, I can comfortably run a pair of 400W panels on each side of the roof (or even side of the vehicle):

    28+28 (per side) = 56A, still well within the 100/*50* 's capabilities.

    In reality on a clear, sunny but less than a blazing day you'd probably get 20-25% less voltage and this less amperage.

    TRUE or UNTRUE? Why?

    (This defines which BlueSolar controllers I will buy.)
    Last edited by Wick; 2020/05/21 at 10:37 PM.

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    Default Re: Amperage for 4x 400W 12/14.4V system

    Why go for two controllers for the 4 panels?

    One Victron 150/35 will do the trick. 2 panels in series, then 2 sets in parallel

    Half the price.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by Wick View Post
    ... 100/*50* 's capabilities.
    Just to make sure ... the 100 is for max volts into the MPPT from the panels.
    The *50* is the max charge current it can send to the batts.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by Prof View Post
    Why go for two controllers for the 4 panels?
    Because of this little titbit ... the fine print as they say.

    Quote Originally Posted by Wick View Post
    I can comfortably run a pair of 400W panels on each side of the roof (or even side of the vehicle) ...
    You can put both arrays on the same MPPT but it is not advisable as it will not produce optimally.

    Different facing arrays is better on 2 x MPPT's.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by the_terrible_triplett View Post

    Different facing arrays is better on 2 x MPPT's.
    Thanks for that info
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Do I miss something in the calcs. 1600/14.4=111.11A

    This is why 2 controllers of more than 50A each should be used. The 100V input would be fine as Prof indicated.

    Back to the drawing board

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    Default Re: Amperage for 4x 400W 12/14.4V system

    Yeah, same difference. You got what I meant - I was using the value for 400W. Thanks for the confirming the thought, @ekkekan.

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    Default Re: Amperage for 4x 400W 12/14.4V system

    Best would be to pull the datasheet and check for both the panels and the charge controller

    BlueSolar Charge Controller MPPT 100/30 MPPT 100/50
    Battery voltage 12/24V Auto Select
    Rated charge current 30A 50A
    Nominal PV power, 12V 1a,b) 440W 700W
    Nominal PV power, 24V 1a,b) 880W 1400W
    Maximum PV open circuit voltage 100V 100V
    Max. PV short circuit current 2) 35A 60A
    Maximum efficiency 98% 98%



    Meaning on a 12v system you can only load 440w on the 100/30 and 700w on the 100/50
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by Wick View Post
    Hello guys,

    This is a very straightforward answer in my opinion, using high-school physics, under IDEAL CONDITIONS:

    W=VA
    1600W = 14.4V (avg) x A
    A = 1600W / 14.4V = +-112A.

    This means for two Victron BlueSolar 100/50s, I can comfortably run a pair of 400W panels on each side of the roof (or even side of the vehicle):
    A bit confucing but yes 1 x Bluesolar 100/50 can take 2 x 400 watt panels max for 12 volt charging.

    In the spec the 1600watt is for 24 volt system, and for 12V system it can charge 700W. Further it can take up 100V input, and charge up to 50amp.
    Last edited by JLK; 2020/05/22 at 10:15 AM.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Now to confuse things a bit more....

    Last time I spoke to experts on the MPPT controllers, they said to try and keep the PV side voltage below 4 times the battery voltage.
    So, with each 400W panel the voltage would be around the 38V mark.
    So yes, 2 x 38V will be under the 100V mark, but it would be 72V.
    72V / 14V = 5 times.

    I would recommend you run all the panels in parallel, thus giving you only 38V on the PV side.
    This should make your MPPT controller work much less with higher overall efficiency.


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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by Wetkit View Post
    Now to confuse things a bit more....

    Last time I spoke to experts on the MPPT controllers, they said to try and keep the PV side voltage below 4 times the battery voltage.
    So, with each 400W panel the voltage would be around the 38V mark.
    So yes, 2 x 38V will be under the 100V mark, but it would be 72V.
    72V / 14V = 5 times.

    I would recommend you run all the panels in parallel, thus giving you only 38V on the PV side.
    This should make your MPPT controller work much less with higher overall efficiency.

    First time I hear of this PV voltage below 4x the battery voltage thing, never seen it mentioned anywhere even on the Victron forums so wonder if it's that big of a deal?
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    Default Re: Amperage for 4x 400W 12/14.4V system

    @Vick have you already got those panels or are you still just playing around with numbers? I assume if you are talking 400W panels that these panels will be fixed to your vehicle?

    Going back to your other thread, what's your plan with the starting battery, do you still want to put solar on it as well?

    Even with the 2 controllers for each pare of panels, I would still wire the panels in parallel. Main reason behind this is shading, if one panel catches shade only that panel will be effected, where if you wire in series, all panels on the string of the panel getting shade will be effected.

    Say panel A and B is on controller 1 and panel C and D on controller 2.
    In series if panel A and C gets shade then your entire array gets dragged down, where if in parallel panel B and D will still go at full capacity while the others are in the shade.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by Wetkit View Post
    Now to confuse things a bit more....

    Last time I spoke to experts on the MPPT controllers, they said to try and keep the PV side voltage below 4 times the battery voltage.
    So, with each 400W panel the voltage would be around the 38V mark.
    So yes, 2 x 38V will be under the 100V mark, but it would be 72V.
    72V / 14V = 5 times.

    I would recommend you run all the panels in parallel, thus giving you only 38V on the PV side.
    This should make your MPPT controller work much less with higher overall efficiency.

    Quote Originally Posted by bigboy529 View Post
    First time I hear of this PV voltage below 4x the battery voltage thing, never seen it mentioned anywhere even on the Victron forums so wonder if it's that big of a deal?
    A very LONG time ago I heard something about that for PWM's yes, but NEVER a word of that for MPPT's.
    I stand to be corrected though, yea?

    Because with MPPT's there are two things to keep in mind:
    1) The minimum volts the MPPT needs to starts up with.
    2) The higher the volts from panels to MPPT the better they work - keeping max volts in mind.

    FWIW: higher volts = lower voltage drop on cables.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by bigboy529 View Post
    @Vick have you already got those panels or are you still just playing around with numbers? I assume if you are talking 400W panels that these panels will be fixed to your vehicle?

    Going back to your other thread, what's your plan with the starting battery, do you still want to put solar on it as well?

    Even with the 2 controllers for each pare of panels, I would still wire the panels in parallel. Main reason behind this is shading, if one panel catches shade only that panel will be effected, where if you wire in series, all panels on the string of the panel getting shade will be effected.

    Say panel A and B is on controller 1 and panel C and D on controller 2.
    In series if panel A and C gets shade then your entire array gets dragged down, where if in parallel panel B and D will still go at full capacity while the others are in the shade.
    As sound as this may be, Rule 1 of solar panels: Don't put panels up where there is potential of shade. Nike it. (... just do it.)

    Methinks. With a MPPT, wire the volts as high as are allowed .. otherwise save money and get a PWM.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by the_terrible_triplett View Post
    As sound as this may be, Rule 1 of solar panels: Don't put panels up where there is potential of shade. Nike it. (... just do it.)

    Methinks. With a MPPT, wire the volts as high as are allowed .. otherwise save money and get a PWM.


    Vick is doing this install on a camper, it's not a fixed home install, that's why I specifically give shading for my reasoning behind parallel connection.

    No matter how hard you try, at some point of the day some part of the vehicle will be in partial shade, unless of course you camp in the middle of a desert where there are no trees.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by bigboy529 View Post
    Vick is doing this install on a camper, it's not a fixed home install, that's why I specifically give shading for my reasoning behind parallel connection.

    No matter how hard you try, at some point of the day some part of the vehicle will be in partial shade, unless of course you camp in the middle of a desert where there are no trees.
    All true. Solar is never easy.

    Still I would chose for higher volts for longest possible times per day ... even consider making panels movable/adjustable.

    350w and larger panels are split already. See here: https://thepowerstore.co.za/products...-hiku-with-mc4
    It is to compensate if one part of the panel is in shade, the other half still works.
    ... just angle the panels that not both sides are in shade at the same time obviously.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by the_terrible_triplett View Post
    All true. Solar is never easy.

    Still I would chose for higher volts for longest possible times per day ... even consider making panels movable/adjustable.

    350w and larger panels are split already. See here: https://thepowerstore.co.za/products...-hiku-with-mc4
    It is to compensate if one part of the panel is in shade, the other half still works.
    ... just angle the panels that not both sides are in shade at the same time obviously.


    Nee wat, if you have panels of that size, you don't want to muck about with moving them around the hole day long. Fixing them is a bit of a compromise, but you try make up for that with capacity.
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by bigboy529 View Post
    Nee wat, if you have panels of that size, you don't want to muck about with moving them around the hole day long. Fixing them is a bit of a compromise, but you try make up for that with capacity.
    Interestingly, they are quite "light".
    I carried mine around with relative ease ... just don't let the wind grab it though. ;-)
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    Default Re: Amperage for 4x 400W 12/14.4V system

    Quote Originally Posted by bigboy529 View Post
    @Vick have you already got those panels or are you still just playing around with numbers? I assume if you are talking 400W panels that these panels will be fixed to your vehicle?

    Main reason behind this is shading, if one panel catches shade only that panel will be effected, where if you wire in series, all panels on the string of the panel getting shade will be effected.
    I wonder who have actually checked what power they get when say one panel in a string in series has some shade. I recently covered more than 50% of a panel and due to the bypass diodes fitted in all panels these days the total output did not drop more than about 30%. This test was done by shading a portion of each panel to ensure that all their diodes were in fact working as they should.

    Don't we sometimes make a small problem into something much larger?

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