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    Solar System Battery Chargers

    Hello All,

    I wanted to share a solar distribution setup I saw at a remote telemetry station and wanted to hear your thoughts. This telemetry station consists of a 48V solar panel feeding a charge controller which feeds a string of battery totaling 48Volts. There is a second load charger which "transfers" the energy from the same battery to the DC load. Both chargers are from the same vendor - Morningstar. I was wandering why they would use two battery chargers, instead of one battery charger and one power supply. I'd think a 48Vdc-48Vdc power supply would provide stable voltage for the load and filter out any "irregularities" on the input.

    Thoughts?

    Thanks,
    EE

    #2
    My guess is either someone didn't know what they were doing or there is something you've left out or described incorrectly.

    Comment


      #3
      Initial thought is the second controller could be:

      1. A DC DC converter to change or stabilize the battery voltage (48v bank will be between 46 and 60 volts)

      2. An inverter.

      3. Some sort of load manager/controller.

      4. A diversion charge controller where the first controller is used for it's mppt and/or DC DC converter capabilities and not charge control (seems unlikely from your description).

      But I don't believe Morningstar makes anything for numbers 1-3, so I think we are back to JB's response
      Ethan Brush - East West Electric. NY, WA. MA

      "You can't generalize"

      Comment


        #4
        I would say the "load charger"is not a charger but either a DC power supply or an AC inverter. Morningstar does make an inverter.

        Comment


          #5
          Originally posted by pv_n00b View Post
          . Morningstar does make an inverter.
          And it's a great little inverter with very low standby losses, but only for 12V . Maybe it's a 12Volt bank not a 48 as the OP thought.
          Ethan Brush - East West Electric. NY, WA. MA

          "You can't generalize"

          Comment


            #6
            Greetings,

            The two devices in question are Morningstar TS-MPPT-60 and Morningstar TS-45. The system is indeed a 48VDC system.

            Thanks,
            EE

            Comment


              #7
              The TS45 has a diversion feature so that's almost certainly what it's being used for.

              The MPPT-60 will be better at harvesting energy from the array, because its MPPT, but it does not appear to have a diversion feature.

              So someone wanted to utilize a diversion load when batteries were full but didn't want to compromise on energy harvest, and spent extra money to get both features.

              I think we figured this out.

              Comment


                #8
                .... unless it's being used as a load controller. those TS controllers are able to do 3 modes, one of them being load control. I don't know offhand how the load control functionality is used. You could download the manual and read about it.
                Ethan Brush - East West Electric. NY, WA. MA

                "You can't generalize"

                Comment


                  #9
                  Many telecommunications systems use a -48V (positive is grounded), but the Morningstar controllers are for a negative ground system. It is possible to isolate the array and controller and then ground the battery negative. This works for the charge function, but not for the load if a low voltage disconnect is needed. A work around is often a second controller and a relay for load control. The second controller does not need MPPT.

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