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  • Solar charge controllers

    Hi, I'm new to solar... I would like to power 2 x garden water features with a solar panel, charge controller and battery combination. The pumps are 12Vdc, 20W each. What I'm not sure about is how charge controllers function.
    Scenario 1: If it is daytime with sun exposure on the panel, and the battery is fully charged, will the charge controller still run the pumps directly from the panel?
    Scenario 2: If the pumps have run overnight, and the battery has discharged considerably, will the charge controller cut the supply to the pumps in the daytime with full sun exposure to prioritize charging the battery? I have seen how the PWM charge controllers control battery charge as opposed to the MPPT, but does either have the ability to overcome both scenarios above to maximize water feature availability?

  • #2
    Originally posted by farsouth View Post
    Scenario 1: If it is daytime with sun exposure on the panel, and the battery is fully charged, will the charge controller still run the pumps directly from the panel?
    That is how all battery chargers works assuming the panels have the capacity to handle the load. If not the battery has to make up for the shortage.

    Originally posted by farsouth View Post
    Scenario 2: If the pumps have run overnight, and the battery has discharged considerably, will the charge controller cut the supply to the pumps in the daytime with full sun exposure to prioritize charging the battery?
    No charger does that. It has no control what so ever where power goes. you can make or buy something to do that, but no a charge controller on its own cannot do that.

    Originally posted by farsouth View Post
    I have seen how the PWM charge controllers control battery charge as opposed to the MPPT, but does either have the ability to overcome both scenarios above to maximize water feature availability?
    Makes no difference what kind of controller you have. They both have outputs. Voltage and current do not change behaviour and must follow Ohm's Law. The only control they might have as it is optional is a Low Voltage Disconnect on a second output that is routed through a Relay. Issue with that is they are very low power and useless unless you build another relay circuit to control connection to the battery as above. Most use an Inverter which should have a LVD circuit built in.
    Last edited by Sunking; 12-19-2016, 12:38 PM.
    MSEE, PE

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    • #3
      Do you need to run at night or the evening? One option is to use a Linear Current Booster with a 200W panel and operate without a battery . These boosters are around $250. I should make them as they are only worth about $12 in that power range. You could use a controller with a light feature. I have a Morningstar that operates a light 2hrs after dusk and before dawn or other combinations. Add to that a Low Voltage Disconnect and the pumps will only start operating when the battery is sufficiently charged as opposed to just dropping out when it is near death.

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      • #4
        I would like them to run throughout the day and then maybe until midnight. I'm assuming the linear current booster will only allow me to run during the day...The controller with the light feature - does this mean it checks the power received from the solar panel and determines whether its day/night, or does it have some sort of light dependant resistor to gauge the time of day, or does it have some real time clock for timing functions? I will have a look at the Morningstar range anyhow...

        From what Sunking has mentioned, this means that even if you don't have a battery connected to a charge controller, you can still drive the load, using the charge controller as the regulator in the circuit...

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        • #5
          Originally posted by farsouth View Post
          I would like them to run throughout the day and then maybe until midnight. I'm assuming the linear current booster will only allow me to run during the day...The controller with the light feature - does this mean it checks the power received from the solar panel and determines whether its day/night, or does it have some sort of light dependant resistor to gauge the time of day, or does it have some real time clock for timing functions? I will have a look at the Morningstar range anyhow...

          From what Sunking has mentioned, this means that even if you don't have a battery connected to a charge controller, you can still drive the load, using the charge controller as the regulator in the circuit...
          Most of the controllers that have a "light sensor load control" do use the PV panel as a light sensor.
          Most controller Load outputs, have a limited power that can be drawn through the internal circuity, so you need to carefully check your load power and insure that it is within the safe limits of the load control.
          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

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          • #6
            Originally posted by farsouth View Post

            From what Sunking has mentioned, this means that even if you don't have a battery connected to a charge controller, you can still drive the load, using the charge controller as the regulator in the circuit...
            NO! You are misreading what SK is trying to tell you.

            There is no reason that a CC could not be build that way, but to the best of my knowledge none are.
            They all require constant battery power to operate the internal circuitry and also rely on the battery to filter the pulsed output current from the CC to a DC voltage with minimal ripple.
            All but a few CCs require that you connect to the battery before you connect to the PV, otherwise the CC will not initialize properly.

            A linear current booster, OTOH, is specifically designed to run without a battery AND it takes advantage of the fact that the power drawn by the pump varies with applied voltage in order to match the power consumption of the pump to the instant available power from the panels.
            A CC will try to deliver an output voltage in the ball park of the nominal battery voltage and if the pump draws too much power at that voltage for the PV to keep up, it will just shut down completely.
            SunnyBoy 3000 US, 18 BP Solar 175B panels.

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            • #7
              Originally posted by farsouth View Post
              From what Sunking has mentioned, this means that even if you don't have a battery connected to a charge controller, you can still drive the load, using the charge controller as the regulator in the circuit...
              No Sir I never said any such thing.
              MSEE, PE

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              • #8
                Hi Im also new to solar and hope someone can help me.

                I have installed 4 x 160 watt 12 volt panels on a boat. I need to charge 4 x 200 amp hour 12 volt batteries system that is linked together to form a 24 volt system. I have connected 2 panels parallel and 2 in series to try and obtain 36 volts but the maximum I can get from the panels is 24 volts and now on my 2nd controller (30 amp) in 4 weeks. Should I get a high quality controller with maybe higher amps or should I put all panels in series to get 48 volt output? I hope some one can assist me Thanks Russell

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                • #9
                  Thanks Gents, this is valuable information that I can use to make a more informed decision as I will be spec'ing this system early next year.

                  Merry Xmas to all and to all the solar enthusiasts wishing you a BRIGHT new year!!!
                  Last edited by farsouth; 12-21-2016, 06:39 AM.

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                  • #10
                    Originally posted by bigruss View Post
                    Hi Im also new to solar and hope someone can help me.

                    I have installed 4 x 160 watt 12 volt panels on a boat. I need to charge 4 x 200 amp hour 12 volt batteries system that is linked together to form a 24 volt system. I have connected 2 panels parallel and 2 in series to try and obtain 36 volts but the maximum I can get from the panels is 24 volts and now on my 2nd controller (30 amp) in 4 weeks. Should I get a high quality controller with maybe higher amps or should I put all panels in series to get 48 volt output? I hope some one can assist me Thanks Russell
                    I may be a little confused by your panel wiring description but IMO if you wire 2 of those panels in series you should get about 35 - 36volts with charging amps = the Imp of one of those panels.

                    Wiring a second set of 2 series wired panels in parallel to the first set of 2 should still get you about 35 - 36 volts with double the charging amps to ~ 2 x Imp of one of those panels.

                    You did not state what your CC was but I am hoping it is an MPPT or you will not be taking full advantage of the total 640 watts of the 4 panels.

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