parallel & series wiring solar panels

kurt
kurt Registered Users Posts: 13
would someone please explain the parallel and series wiring of solar panels . i understand that if i take 4 golf cart batt and do the parallel/series wiring that it will be 12v @ 400 ah . but i fail to see what would be the best way of hooking up 2 panels or more panels to charge the 4 batteries.

Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: parallel & series wiring solar panels

    Depends on your controller and it's ability,

    If you only have a 12volt controller you will have to wire your panels in parallel to keep the voltage correct. If you have a mppt type controller that will accept higher input voltages (above 12vdc,, 24, 48, etc) and then down convert back to 12vdc,, you can run any configuration you wish,,, with the higher voltages generally being better because you have less loss through the wiring.

    In short,, think of the panels as a collection of batteries. You can wire them in any configuration of series, parallel or series parallel that you wish,,, assuming the controller can handle the input voltage and current.

    Does this answer your question?

    Tony
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: parallel & series wiring solar panels
    kurt wrote: »
    would someone please explain the parallel and series wiring of solar panels . i understand that if i take 4 golf cart batt and do the parallel/series wiring that it will be 12v @ 400 ah . but i fail to see what would be the best way of hooking up 2 panels or more panels to charge the 4 batteries.

    Um.

    Assuming that these are standard T-105 (105ah@6v) type golf cart batteries, 4 of them won't give you 400 ah @ 12v.

    Two (a set), wired in series will give you 105 ah @ 12v, two sets wired in parallel will then give you 210ah @ 12v.

    or

    Two (a set) wired in parallel will give you 210 ah @ 6v, then two sets wired in series will give you 210ah @ 12v.


    Also, from what I've read here (I've never done a solar install yet), wiring panels in series will cause the entire array (of panels) to put out less current if part of the array is in shadow, whereas wiring the array in parallel will cause only the panel which is shadowed to put out less while those panels still in full sunlight will still put out full power.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: parallel & series wiring solar panels

    DWH does make a good point. In any series panel wiring,, shading on any portion of any one panel will reduce (significantly) the production of the entire string. Panel configuration should be made in consideration with the effects of wire runs, shading in mind,,, amongst other things.

    Tony
  • kurt
    kurt Registered Users Posts: 13
    Re: parallel & series wiring solar panels

    yeah that does explain it pretty good . my charge controller is 12 v @ 30 amps DHW ,my bad it's not no 400 , according to the web site it's 220
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: parallel & series wiring solar panels

    What brand/model controller? As I suggest, if you have an mppt controller you can still wire panels in series.

    Tony
  • kurt
    kurt Registered Users Posts: 13
    Re: parallel & series wiring solar panels

    It's a '' sunforce '' from notheren tools 12v ( 12v only ) 30 amps and can handle up to 400 watts . i'll keep lookin through the owners manual on that mppt but it does say to add panels in parallel
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: parallel & series wiring solar panels
    kurt wrote: »
    yeah that does explain it pretty good . my charge controller is 12 v @ 30 amps DHW ,my bad it's not no 400 , according to the web site it's 220

    12v@30a output or input?

    From what I've read here, and if I understand what I've read correctly...

    IF the array will be in full sunlight, and IF the CC (or inverter) can handle the incoming voltage, then it's probably better to wire the panels in series to push the current at a higher voltage.

    BUT

    You have a similar issue with the panels that you do with the batteries, you need to get them to put out a voltage (and amperage) that is compatible with what is at the other end.

    (In the battery example, we need them to put out 12v for the loads, but with the panels we need them to put out both voltage and amperage that are compatible with the charge controller or inverter (or both) that we have at the other end.)

    So it's nearly same thinking with the panels as it was for the batteries.

    For example, let's assume the panels put out 5amps at 12v.

    Let's also assume that the controller can handle 24v incoming (I'm ignoring controller input amperage for the moment) and we'll further assume that you have say 4 panels, then you could:

    1) Wire two panels in series to get a 5a@24v set, then wire the other two in series to get another 5a@24v set - and then parallel the two 24v sets to get 10a@24v.

    2) Parallel two of them to give 10a@12v, parallel the other two and get another 10a@12v and then series those two sets to get 10a@24v - same result.

    3) You could simply parallel all 4 panels to get 20a@12v.

    But what you CAN'T do is series all 4 panels, because that would give you 48v and be too much for the input of the controller.


    You have the same issue with the amperage - you can't arrange a panel array that puts out more amperage than the device at the other end can handle.(The voltage and amperage are tied together, you need to always consider them as a matched pair - can't change one without changing the other.)

    For instance, say the controller could accept input of 15a@24v. Looking at the examples above, you could use either #1 or #2, but you could NOT use #3 because it would result in too high of an amperage for the controller's input.



    Keep in mind, these are just examples to make the concept easy to grasp. In truth, most 12v panels put out more like 17v-20v, and a controller than can accept 24v will probably be built to also handle 36v (or more) so you have to do the math using the real numbers from the product specs in order to get it right.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: parallel & series wiring solar panels

    From northern it is a simple 12 vdc in/out controller,,, no mppt.

    Sorry DWH but you are making it too complicated. The controller will only handle 12vdc input,,, and 12vdc output. (Nominal)

    Wire your panels in parallel,, 12 vdc.

    T
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: parallel & series wiring solar panels
    icarus wrote: »
    Sorry DWH but you are making it too complicated.

    Well, the original post DID say:

    "would someone please explain the parallel and series wiring of solar panels"

    So I explained (in simple terms and as best I could from my limited knowledge).


    (And - I started my explanation post before he posted the model of CC, so I didn't see that until after I posted.)
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: parallel & series wiring solar panels

    No worries,,just trying to keep it simple,

    Tony