Panel Configuration





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  1. #1
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    Default Panel Configuration

    I need some help/advice.

    Have 14 x 80W panels
    Have 150V70A MPPT Charge controller

    How would you configure them for the MPPT?

    I suspect 7 panels in series and then 2 banks might take me past the 150V limitation.
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    Default Re: Panel Configuration

    Look at the label on the back

    What is the Voc = ?

    Multiply that with the number of panels in series then see if you are over 150V
    Last edited by Dungbeetle; 2020/07/28 at 01:06 PM.
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  3. #3
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    Default Re: Panel Configuration

    With the panels watts, ideally need this 6 values (in the 2 red boxes) ... with them temp coefficients being the straws that can break the camels back, as they say, IF you want to run on the edge.
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    Default Re: Panel Configuration

    Quote Originally Posted by Prof View Post
    I need some help/advice.

    Have 14 x 80W panels
    Have 150V70A MPPT Charge controller

    How would you configure them for the MPPT?

    I suspect 7 panels in series and then 2 banks might take me past the 150V limitation.
    Normally 36 cell 80W panels have a Voc at about 22 to 23V. Yes 7 will exceed the max on the controller.

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    Default Re: Panel Configuration

    Also check the charge current in the case of 12V that it dont exceed 70 Amp.
    Johan Kriel

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    Default Re: Panel Configuration

    Quote Originally Posted by ekkekan View Post
    Normally 36 cell 80W panels have a Voc at about 22 to 23V. Yes 7 will exceed the max on the controller.
    3 different makes of panels.

    Voc of one make is 21.6V

    That takes me past 150V.

    Now what other configuration can I do?

    6/4/4 or 5/5/4 or 4/4/4/2 etc?

    Or just loose two and go 6/2?
    Robert van den Berg

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  7. #7
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    Default Re: Panel Configuration

    It seems like 4 in series and 4 parallel strings with 1 panel not used. This looks like around 35A which is far below the 70A of the controller.

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    Default Re: Panel Configuration

    Quote Originally Posted by JLK View Post
    Also check the charge current in the case of 12V that it dont exceed 70 Amp.
    I am ok on that. Currently running 12 panels in 6/2 config on 150V35A MPPT.
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    Default Re: Panel Configuration

    Quote Originally Posted by ekkekan View Post
    It seems like 4 in series and 4 parallel strings with 1 panel not used. This looks like around 35A which is far below the 70A of the controller.
    So it is ok to do one series set with less panels as other sets?

    Wouldn't 2 five in series sets and one four in series set not be ok as well. 3 parallel strings?
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    Default Re: Panel Configuration

    Or 7 banks of 2 each.
    Last edited by JLK; 2020/07/28 at 01:40 PM.
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    Default Re: Panel Configuration

    Quote Originally Posted by Prof View Post
    3 different makes of panels.

    Voc of one make is 21.6V

    That takes me past 150V.

    Now what other configuration can I do?

    6/4/4 or 5/5/4 or 4/4/4/2 etc?

    Or just loose two and go 6/2?
    6/4/4 and 5/5/4 a no go as the mppt will not be able to get the different amount of panels at their MPPT point. 4 times 4 and loose 1 or 6/2 and loose 2.

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  13. #12
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    Default Re: Panel Configuration

    Quote Originally Posted by JLK View Post
    Or 7 banks of 2 each.
    Can also work
    Last edited by ekkekan; 2020/07/28 at 01:49 PM.

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    Default Re: Panel Configuration

    Quote Originally Posted by ekkekan View Post
    6/4/4 and 5/5/4 a no go as the mppt will not be able to get the different amount of panels at their MPPT point. 4 times 4 and loose 1 or 6/2 and loose 2.
    Thanks. That answers my doubt if it will work with unequal series strings.

    Have to save up for two more 80W panels
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    Default Re: Panel Configuration

    ignore
    Last edited by JLK; 2020/07/28 at 01:56 PM.
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    Default Re: Panel Configuration

    Quote Originally Posted by JLK View Post
    Or 7 banks of 2 each.
    Nogal...

    Victron MPPT calc site says that 150V35A MPPT will also work on that.

    One never thinks of smaller series strings.
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    Default Re: Panel Configuration

    Quote Originally Posted by Prof View Post
    Nogal...

    Victron MPPT calc site says that 150V35A MPPT will also work on that.

    One never thinks of smaller series strings.
    Haven't check, not sure if you charge say 36 volt if it will work?
    Johan Kriel

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    Default Re: Panel Configuration

    Quote Originally Posted by JLK View Post
    Also check the charge current in the case of 12V that it dont exceed 70 Amp.
    It's the voltage which kills - keep the total panel Voc voltage to less than the max rating of the controller.

    But the controller should not blow if your panels are within the voltage spec, but could deliver more current than the controller rating - the controller will only deliver the max rated amps, irrespective of what's available on tap behind it. I suppose it's similar to connecting a 6A battery charger to an Eskom source, which can deliver much more than 6A.
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    Default Re: Panel Configuration

    Quote Originally Posted by mikeml View Post
    . I suppose it's similar to connecting a 6A battery charger to an Eskom source, which can deliver much more than 6A.
    I agree. It is amazing how many posts we see with respect to the max amps. This does not normally fry a controller as the voltage does if the max is exceeded. Also a number of inverters can accept more panels in Watts than what the spec says and it will just limit what can be used and helps outside the 11h to 14h peak sun period.
    Last edited by ekkekan; 2020/07/28 at 06:39 PM.

  20. #19
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    Default Re: Panel Configuration

    Quote Originally Posted by mikeml View Post
    It's the voltage which kills - keep the total panel Voc voltage to less than the max rating of the controller.

    But the controller should not blow if your panels are within the voltage spec, but could deliver more current than the controller rating - the controller will only deliver the max rated amps, irrespective of what's available on tap behind it. I suppose it's similar to connecting a 6A battery charger to an Eskom source, which can deliver much more than 6A.
    Maximum PV open circuit voltage of 150v yes.
    As bad is that is the Maximum PV short circuit current, being 50amps on the 150/70 (or max 30A per MC4 connecter).

    The 150/70, the 70 part is the Rated charge current i.e. the max amps it can charge the batteries at, being 70amps.
    That is a battery bank of wot, +-700ah at 10% charge rate.

    A MPPT can only produce what is drawn on the DC side and that production is completely reliant on what the panels can produce.
    I.e. if the DC side needs 70amps at 12v and the panels can only produce 10w, then 10w is all you are going to get from that MPPT.
    Conversely, if you have 4000 watts of panels installed and the DC side needs 10w, then 10w is all you are going to get from that MPPT.

    A 80w panel, per watt, is quite expensive compared to larger panels ... and required more mounting parts. Just saying.

    14 x 80w panels = 1120w = +-900w on average on a good day all things being equal.


    Bottom line - on ALL MPPT's:
    Don't ever exceed that Maximum PV open circuit voltage.
    Don't ever exceed that Maximum PV short circuit current.

    If one does exceed either, then Phone Life Line. Find their no. in the Yellow Pages.
    Why?
    Because maybe they would care that you let the smoke out, as no-one else would.
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  22. #20
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    Default Re: Panel Configuration

    Quote Originally Posted by the_terrible_triplett View Post
    ......

    A 80w panel, per watt, is quite expensive compared to larger panels ... and required more mounting parts. Just saying.

    14 x 80w panels = 1120w = +-900w on average on a good day all things being equal.

    The 80W's I have....so use them

    Mounting, easy. Screw two long purlins onto roof and mount with coach screws and fender washers, dis mos op die plaas stoor se dak

    Robert van den Berg

    1998 Daihatsu Rocky 'The Kitty'
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    "Socialism only works in two places: Heaven where they don't need it and hell where they already have it." -Ronald Reagan.

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