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  • Solar Charge Controllers - Multiples

    I am a total newbie pondering the hooking up of Solar Panels,

    I've a question regarding hooking up multiple units of the Solar MPPT charge controller -

    If your load requirement is such that, then you need multiple MPPT charge controller for your PV system. I see that, in Xantrex manuals, that you have to hook up separate arrays (no mixup) to each charge controller and hence consequently to the separate battey banks .... So, will this set of wires form a separate circuit all the way through? Where/how do they join at some place such as inverter, circuit breakers ??? Apart from this, is there any disadvantages to this kind of connection such as with state of charge unequal among different battery banks!?

    Thanks in anticipation,

  • #2
    Originally posted by solarponders View Post
    If your load requirement is such that, then you need multiple MPPT charge controller for your PV system. I see that, in Xantrex manuals, that you have to hook up separate arrays (no mixup) to each charge controller and hence consequently to the separate battey banks ....
    No that is not correct.

    If you have more panel wattage than your controller can input, then you must use 2 or more controllers as separate solar panel arrays. However there is no problem for multiple controllers to serve a common battery if that is what you want to do. In fact Xantrex makes a communication cable to wire between controllers to do exactly that function. You program one controller to be the Master, and the rest are Slaves.
    MSEE, PE

    Comment


    • #3
      Originally posted by Sunking View Post
      No that is not correct.

      If you have more panel wattage than your controller can input, then you must use 2 or more controllers as separate solar panel arrays. However there is no problem for multiple controllers to serve a common battery if that is what you want to do. In fact Xantrex makes a communication cable to wire between controllers to do exactly that function. You program one controller to be the Master, and the rest are Slaves.
      Got it thanks.

      Comment


      • #4
        Originally posted by solarponders View Post
        I am a total newbie pondering the hooking up of Solar Panels,

        I've a question regarding hooking up multiple units of the Solar MPPT charge controller -

        If your load requirement is such that, then you need multiple MPPT charge controller for your PV system. I see that, in Xantrex manuals, that you have to hook up separate arrays (no mixup) to each charge controller and hence consequently to the separate battey banks .... So, will this set of wires form a separate circuit all the way through? Where/how do they join at some place such as inverter, circuit breakers ??? Apart from this, is there any disadvantages to this kind of connection such as with state of charge unequal among different battery banks!?

        Thanks in anticipation,
        Are you asking if one PV array, can serve several MPPT controllers for different battery banks ?
        Generally, I would say no, as the MPPT controllers each try adjusting the array voltage, to get the best power from the panels, and if 2 of them hit the array at the same time, both or none, coudl be unhappy. Nothing harmed, but you could have some harvest loss, depending on how many MPPT's are trying to "Sweep" or Load" the array at the same time.

        If you are needing to charge a large battery bank, I would size an array to be 120%- 140% of the wattage the MPPT could handle, and give each MPPT it's own array. I'd also likely offset each array + or - 10 degrees to "widen" your harvest window, so they all don't "peak" at the same time, unless your daytime loads also peak at that time.
        spreadsheet based voltage drop calculator:
        http://www.solar-guppy.com/download/...calculator.zip
        http://www.solarpaneltalk.com/showth...oss-calculator

        http://www.mike-burgess.org/PVinfo_2.html

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister ,
        battery lugs http://tinyurl.com/LMR-BigLug
        Setting up batteries http://tinyurl.com/LMR-NiFe

        gear :
        Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||

        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||

        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        Comment


        • #5
          Originally posted by Mike90250 View Post
          Are you asking if one PV array, can serve several MPPT controllers for different battery banks ?
          Generally, I would say no, as the MPPT controllers each try adjusting the array voltage, to get the best power from the panels, and if 2 of them hit the array at the same time, both or none, coudl be unhappy. Nothing harmed, but you could have some harvest loss, depending on how many MPPT's are trying to "Sweep" or Load" the array at the same time.

          If you are needing to charge a large battery bank, I would size an array to be 120%- 140% of the wattage the MPPT could handle, and give each MPPT it's own array. I'd also likely offset each array + or - 10 degrees to "widen" your harvest window, so they all don't "peak" at the same time, unless your daytime loads also peak at that time.
          Thanks a lot Mike & Sunking, Now again the same question, with the some specifics :

          I've 220w panels, 8.2 amp (Impp) 29.x (Vmpp)

          I am planning to wire them as :

          One string of 2 connected in series to a 30 amp Charge Controller,
          &
          One string of 2 connected in series to a 30 amp Charge Controller,

          My Inverter is 3.5 KVA 48 v.

          My Batteres are 150Ah 12 v. So, I need to have 4 of them in series to make 48v to match the inverter's input
          voltage.

          Now, how would I connect multiple controllers to serve a common battery bank.. without
          the special communication cable to mediate between Charge controllers?

          My uneducated guess is :

          (Dots are just used as filler space as the formatting gets
          screwed up with just white spaces)


          CC1+..........................CC1-.....CC2+...........................CC2-
          |................................|..........|..... ............................|
          +:::B1:::-........+:::B2:::-.........+:::B3:::-..........+:::B4:::-
          |................................................. .............................|
          IV+............................................... ............................IV-

          In the above :

          B1, B2, B3, B4 are connected in series
          CC1, CC2 are not connected


          CC1, CC2 = ChargeControllers
          IV = INVERTER
          B1,B2,B3,B4 = Batteries

          Will the above work?
          Last edited by solarponders; 03-11-2012, 04:00 AM. Reason: typos

          Comment


          • #6
            Originally posted by solarponders View Post
            I've 220w panels, 8.2 amp (Impp) 29.x (Vmpp)

            I am planning to wire them as :

            One string of 2 connected in series to a 30 amp Charge Controller
            One string of 2 connected in series to a 30 amp Charge Controller

            My Inverter is 3.5 KVA 48 v.

            My Batteres are 150Ah 12 v. So, I need to have 4 of them in series to make 48v to match the inverter's input
            voltage.
            OK. So you have two solar arrays, each one ~60V and ~8A, and one 48V battery bank. In that case nothing special is needed. Configure the MPPT charge controller for 48V output, connect each array to one MPPT, and connect the output of both charge controllers across the 48V battery. Separate fuses or circuit breakers strongly recommended.

            Alternatively if both arrays are aimed at the same angle you should be able to use one charge controller for all four panels (connect the array 2s2p.)

            Comment


            • #7
              Originally posted by solarponders View Post
              I've 220w panels, 8.2 amp (Impp) 29.x (Vmpp)

              I am planning to wire them as :

              One string of 2 connected in series to a 30 amp Charge Controller,
              &
              One string of 2 connected in series to a 30 amp Charge Controller,

              My Inverter is 3.5 KVA 48 v.

              My Batteres are 150Ah 12 v. So, I need to have 4 of them in series to make 48v to match the inverter's input
              voltage.


              Will the above work?
              Not really at least not very good if at all. Problem is MPPT controllers are really great at down converting voltages, but terrible at up converting. Just about all MPPT controllers minimum Vmp working voltage is 60 volts, and you are looking at 58 volts. At 48 volts battery they work best @ 66 to 100 volts.

              Quit frowning because you do have an excellent work around providing your Charge Controller can do this. Wire all 4 panels in series. Check the input voltage range for your charge controller. Most of the good ones will go to 150 volts, if so you are in biz.
              MSEE, PE

              Comment


              • #8
                Originally posted by billvon View Post
                OK. So you have two solar arrays, each one ~60V and ~8A, and one 48V battery bank. In that case nothing special is needed. Configure the MPPT charge controller for 48V output, connect each array to one MPPT, and connect the output of both charge controllers across the 48V battery. Separate fuses or circuit breakers strongly recommended.

                Alternatively if both arrays are aimed at the same angle you should be able to use one charge controller for all four panels (connect the array 2s2p.)
                @ billvon, sunking
                my problem is - to do the 2s 2p or 4s array to 1 cc, need more than 30 amps charge controller - which am finding it difficult to get as lots of vendors/manufacturers here (chennai, india) do not carry MPPT >30 amp. am trying to import a xantrex mppt 60 amps from US. but shipping costs a huge chunk.. and am insistent on MPPT type, because it could provide me more in the hot summer days ... we have many many hot days here in our tropical region. and, do remember reading that the MPPT will give more power during those times.

                Comment


                • #9
                  Originally posted by solarponders View Post
                  @ billvon, sunking
                  my problem is - to do the 2s 2p or 4s array to 1 cc, need more than 30 amps charge controller - which am finding it difficult to get as lots of vendors/manufacturers here (chennai, india) do not carry MPPT >30 amp. am trying to import a xantrex mppt 60 amps from US. but shipping costs a huge chunk.. and am insistent on MPPT type, because it could provide me more in the hot summer days ... we have many many hot days here in our tropical region. and, do remember reading that the MPPT will give more power during those times.
                  Not sure what you are getting at but operating on a 48 volt battery with 880 watts panel only needs a single 20 amp charge controller. 880 watts / 48 volts = 18.3 amps.

                  A true 30 amp MPPT charge controller operating on a 48 volt battery system can have a panel wattage of 30 amps x 48 volts = 1440 watts.
                  MSEE, PE

                  Comment


                  • #10
                    Originally posted by solarponders View Post
                    @ billvon, sunking
                    my problem is - to do the 2s 2p or 4s array to 1 cc, need more than 30 amps charge controller
                    Hard to say without knowing which charge controller you are looking at. But I'll pick one for the sake of argument - the SB3048 by Blue Sky. It has the following statement in its manual:

                    "To be compliant with National Electrical Code (NEC), solar module controllers should be sized for 125% more rated capacity than
                    the 25

                    Comment


                    • #11
                      Originally posted by Sunking View Post
                      Not sure what you are getting at but operating on a 48 volt battery with 880 watts panel only needs a single 20 amp charge controller. 880 watts / 48 volts = 18.3 amps.

                      a true 30 amp MPPT charge controller operating on a 48 volt battery system can have a panel wattage of 30 amps x 48 volts = 1440 watts.
                      sorry, you are correct, am mixing it up with numbers got from 24v calculation. have upgraded my inverter to 3.5 kva/48v.
                      so now, i do need only 920/48 = 19 ~ 20 amps + 25% ~ 25 amps.. and even after applying 25%.
                      (infact got the forumula from you 920w/24v = 38 amp, my userid wanna-be-solar got messed up with login).

                      Comment


                      • #12
                        [QUOTE=billvon;41938]Hard to say without knowing which charge controller you are looking at. But I'll pick one for the sake of argument - the SB3048 by Blue Sky. It has the following statement in its manual:

                        "To be compliant with National Electrical Code (NEC), solar module controllers should be sized for 125% more rated capacity than
                        the 25

                        Comment


                        • #13
                          Originally posted by solarponders View Post
                          ....

                          My uneducated guess is :

                          (Dots are just used as filler space as the formatting gets
                          screwed up with just white spaces)


                          CC1+..........................CC1-.....CC2+...........................CC2-
                          |................................|..........|..... ............................|
                          +:::B1:::-........+:::B2:::-.........+:::B3:::-..........+:::B4:::-
                          |................................................. .............................|
                          IV+............................................... ............................IV-
                          I'm not following it.

                          I'd do :

                          CC1+..........................CC1-
                          CC2+..........................CC2-
                          ..+ b a t t e r y 4 8 v -

                          Wire controllers in parallel.

                          And as others say, you seem to be miscalculating your system power
                          spreadsheet based voltage drop calculator:
                          http://www.solar-guppy.com/download/...calculator.zip
                          http://www.solarpaneltalk.com/showth...oss-calculator

                          http://www.mike-burgess.org/PVinfo_2.html

                          solar: http://tinyurl.com/LMR-Solar
                          gen: http://tinyurl.com/LMR-Lister ,
                          battery lugs http://tinyurl.com/LMR-BigLug
                          Setting up batteries http://tinyurl.com/LMR-NiFe

                          gear :
                          Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||

                          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||

                          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                          Comment


                          • #14
                            Originally posted by Mike90250 View Post
                            I'm not following it.

                            I'd do :

                            CC1+..........................CC1-
                            CC2+..........................CC2-
                            ..+ b a t t e r y 4 8 v -

                            Wire controllers in parallel.

                            And as others say, you seem to be miscalculating your system power
                            if I've to do that way,

                            how would I ? Meaning, CC1 is hooked up to a PV and CC2 is tied to another PV array.
                            Now, how would I hook up the CC1 and CC2 in parallel?
                            would I hookup the battery +, - of CC1 with CC2's and CC2's to battery?
                            Is there a provision to do that .. meaning at the terminals I thought only one
                            set of wires can go in.

                            as I said, am not electrical savvy .. just trying to undrestand the diagrams from
                            theory to practice.

                            Comment


                            • #15
                              I have an 80A MPPT Charge Controller and a cheap 40A PWM controller fed from separate PV's. This works out just fine as the 80A (MPX80) will stay in Bulk to 14.8V (I have flooded cells)while the cheap ($45) PWM only to 14.4V. Hence the MPPT takes the "Lead" in charging and the PWM is only used for faster charges or heavy loads.
                              1.6Kw of PV, Outback FM80 controller, 40A PWM cheap Chinese controller, 12V 1000 AH of Trojan T105RE batteries, 2.5Kw Aims MSW inverter and 400W TSW inverter.

                              I will respect other peoples threads and try to stay ON TOPIC. Equally if I start a thread, and in order to keep forum friction to a minimum, only constructive ON TOPIC responses will be answered. Should I still don't reply: It is likely I have blocked you. for being B.A.D. (Belligerent And Derisive)

                              Comment

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