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  • Strange behaviour off-grid system, Need Help!

    Currently I have a system with 3 solar panels of 315W each, + 2 batteries of 120A each, a solar controller of 80A max, and a converter of max 3000W output.

    Now, the problem I have with it is that it barely charges to full capacity. I have 3 displays showing me the battery percentages but all show very different levels of charging.

    One is the 3000W converter that after few days of sun, it reaches 4 lines barely (100%). But most of time is 3 lines or 2.
    Second is an independent voltmeter display I got for 5 bucks on amazon, that shows the most positive prospect, above 80% most of the time. never goes lower than 70%.
    And the third one, is the one of the solar controller, that never went above 75% in terms of battery capacity. Stays within 50%-75% whatever I do.

    So my problem is what can I do to get a proper measurement of how charged these batteries are?
    Could be that I have some connections wrong? or maybe the solar controller is a defective one?
    Does it matter if the batteries are connected in series? as I connected them to have more Ampers? (2x120=240A)

    I'm Attaching also some images for reference, plus the way batteries are connected.
    The Solar controller in sunny days sends about 7-8 Ampers to the batteries, atleast that's what it says.

    The system is connected to a small cabin house to use for 1-2 led light bulbs, and charging phones/laptop. I thought also that maybe the house wires could be old and leak energy somehow, but even when I disconnected the house and tested the batteries alone, the same measurements happen.

    I had previously also another solar charger of 80A but different chinese brand, that was charging much better to my knowledge, but the problem with that was that didn't have this system of shutting off when batteries were full, so they were 'boiling'. Anyway I accidentally burned that one, so I went for this one with this new tech of controlling charging, but I have a feeling is something wrong with this one because I observed when sun is very strong, the controller peaks at 100% shortly and stops charging, which is kind of stupid considering the battery is not full. But probably because it gets suddenly too much energy it thinks the battery is full and it guts the transfer.

    Any ideas what can I do about this? Thanks in advance.

    Attached Files

  • #2
    To get a proper measurement buy a good multimeter. Percentages don't provide much detail without knowing what the reference voltage each device uses for 100%.
    Last edited by Ampster; 08-03-2019, 08:46 AM.

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    • #3
      How do you have your solar panels connected? Series or parallel? One thing definitely wrong is that your controller is a basic PWM controller. It might even say MPPT on it, don't be fooled. The only way to charge a 12 volt battery efficiently is to use 12 volt, 36 cell, panels, wired in parallel. Your panels aren't 12 volt panels so all voltage above 12 to 14.x volts is lost.

      Another thing wrong is you have the PV Off set to 13.7 volts. It should be 14.4 to 14.8 depending on your battery mfg. specs.
      Last edited by littleharbor; 08-03-2019, 09:58 AM.
      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

      Comment


      • #4
        Those inverter cables look terribly small for a 3000 watt 12 volt inverter.
        2.2kw Suntech mono, Classic 200, NEW Trace SW4024

        Comment


        • #5
          How old is the system & the batteries ?

          900+ watts of panels should be able to provide 60A of charge to the batteries at a normal 14V (for a 12V system)

          Areas to check
          What is the internal consumption of the 3,000 w inverter ? Inexpensive inverters often consume a lot of power and can bleed the batteries down.

          Your charge controller does not look capable of 60A and may not be operating correctly. This size of system needs a true MPPT charge controller
          If the controller is a PWM controller, it is throttling your system to only about 400W of power.

          Batteries. You said a different controller was "boiling" them. Were they actually hot, or just bubbling gas from charging. My battery shed sounds like it's full of hissing snakes mid-day, when the batteries are charging hard and bubbling lots of gas. I also use several gallons of distilled water a month. if your batteries are not charging well, and they have been deeply discharged several times, they may be damaged and need replacing.
          Powerfab top of pole PV mount (2) | 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

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

          Comment


          • #6
            Thanks for the fast answers!
            I'll try to offer you some more info and I also attached some images with the technical specs of the solar controller, which actually is just one paper back and forth.
            And the other image is the tech sheet from the manual of the 3000W converter.

            Sorry to put you to work searching info there, but I think is better considering I'm not an expert.

            The Solar panels are connected in Series. They are 3 panels as i said of 315W each, brand is QCells, and here is the tech sheet from the producer:
            Q.PEAK DUO-G5 315-330 (model)
            https://www.q-cells.com/dam/jcr:c674...7_Rev01_EN.pdf

            Regarding the batteries, here is the spec sheet from producer:
            https://centurionbattery.nl/files/da...bustak-120.pdf

            Everything in the system is brand new, and the batteries had maybe 20 cycles or so, but mostly went down to about 50%, so they are not damaged for sure.
            Batteries are also deep cycle to 50%, as the producer says.

            The previous controller was indeed 'boiling', but not heating the battery far as i checked back then, only making noise and bubbling. I red on other websites that is not good, so I thought to disconnect the panels to don't damage the batteries. That's why i searched for this new one.
            On the paper attached they say it is: "compatible MPPT charge controller PWM intelligent/ efficient/ energy saving". You can read the full description on that A5 paper I attached.

            If the controller is indeed the problem, and maybe I should also put panels in parallel? could you recommend me some controllers I can buy here in Europe? Via amazon, or just point some brands and I'll search them locally.

            Other tips are also welcome.
            Attached Files

            Comment


            • #7
              From the photo that charge controller looks like a cheap PWM, so you may be wasting a lot of power from the panels. PWM charge controllers just pull down the voltage but keep the same amperage coming from the panels. For example, the typical 315W panel outputs around 35V and 9A, the charger will take those 35V and convert them to around 14V for a 12V system. Then you get 14V*9A=126W. So your 315W panels are now 126W panels.

              Are the panels connected in series or parallel?

              Also make sure the charging profile of the charge controller matches that of your batteries (charging and float voltages). Well, only of your charge controller allows you to select that.

              A 3000W inverter at 12V would require over 200A, which would need very very thick cables. The current cables look like a fire hazard. Also, that inverter would consume around 50W just for being connected to the batteries, so it could be draining your batteries.

              Finally, that switch between the charge controller and the panels looks like an AC switch, which could also cause a fire. Make sure to use only DC rated switches.
              Last edited by Glock24; 08-03-2019, 04:23 PM.

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              • #8
                hmm, i've posted earlier more details and tech specs, but it said my post is pending approval. do i need to do something else? because i don't see it anywhere now, it just vanished.

                -- edit, now it shows up above the post.
                Last edited by vlad777; 08-03-2019, 04:47 PM.

                Comment


                • #9
                  Thanks to all for the fast answers!

                  I'll try to offer you some more info and I also attached some images with the technical specs of the solar controller, which actually is just one paper back and forth.
                  And the other image is the tech sheet from the manual of the 3000W converter.

                  Sorry to put you to work searching info there, but I think is better considering I'm not an expert.

                  The Solar panels are connected in Series. They are 3 panels as i said of 315W each, brand is QCells, and here is the tech sheet from the producer:
                  Q.PEAK DUO-G5 315-330 (model)
                  https://www.q-cells.com/dam/jcr:c674...7_Rev01_EN.pdf

                  Regarding the batteries, here is the spec sheet from producer:
                  https://centurionbattery.nl/files/da...bustak-120.pdf

                  Everything in the system is brand new, and the batteries had maybe 20 cycles or so, but mostly went down to about 50%, so they are not damaged for sure.
                  Batteries are also deep cycle to 50%, as the producer says.

                  The previous controller was indeed 'boiling', but not heating the battery far as i checked back then, only making noise and bubbling. I red on other websites that is not good, so I thought to disconnect the panels to don't damage the batteries. That's why i searched for this new one.
                  On the paper attached they say it is: "compatible MPPT charge controller PWM intelligent/ efficient/ energy saving". You can read the full description on that A5 paper I attached.

                  If the controller is indeed the problem, and maybe I should also put panels in parallel? could you recommend me some controllers I can buy here in Europe? Via amazon, or just point some brands and I'll search them locally.

                  ​​​​​​​Other tips are also welcome.
                  Attached Files

                  Comment


                  • #10
                    Putting your 3 panels in series, means you are only getting 8 amps into your batteries with your PWM controller. That's not good. You need to obtain a decent 150V MPPT controller and will then be able to put 60A and actually charge the batteries.
                    Powerfab top of pole PV mount (2) | 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

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

                    Comment


                    • #11
                      As everybody else have noted as well, your series wired panels are putting about 8 amps at high voltage into your cheap PWM controller. You would have better performance with a 140 watt 12 volt panel. This is your big problem. Your other problem is the PV off setpoint on your controller is set too low. Your batteries will never get fully charged no matter how many watts you connect. This is a real good example of how NOT to set up your PV system.
                      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                      Comment


                      • #12
                        I would recommend connecting the panels in parallel to get more amps, connect the batteries in series and convert your system to 24V. Both the inverter and charge controller support 24V. That way you'll have fewer losses and you'll get more energy out of your current equipment.

                        As Mike suggested, you should get a good MPPT charge controller.

                        Comment


                        • #13
                          Ok, so the problem so far as I understand is the Controller which throttles the panels, and that I should put the panels in parallel.

                          My question then is, what controller you recommend?
                          Is something like this one on Amazon better? Is this Victron brand good? because I suppose all these Chinese ones are not what i need.

                          And actually what ampers and volts? because I'm not sure I get all these models from Victron, they have some with more volts and less amps, and the other way around.

                          If one of my panel puts around 8A, then 3 panels should be 24A. and the voltage if it is in parallel is what 3x40V= 120V?
                          So should this Victron model do the job? It has 150V and 35A for the specs.




                          Comment


                          • #14
                            That controller should work.
                            Where are you located? The inverter you show is not suited for use in the USA. I presume you know that and are in an area that uses 230 Vac and 50 hz.
                            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                            Comment


                            • #15
                              Yes, I'm based in Netherlands, so Europe, not USA.

                              Just curious, for now I understand that the panels in parallel would give me more amps and keep the voltage at 40v. Since the controller gets in max 14.8 volts, that means with panels in parallel I'll get 14.8 x 24 amps = 355.2w

                              Now with them in series I get 1 third of that.

                              But when I get a different controller that can put in 150volts, does it really matter if the panels are series or parallel?

                              From what I red the big advantage for parallel is only if they are damaged or partially in sun.

                              ​​​​ Am I right? Or just got it wrong?



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