Charging or Discharging / Buying or Selling

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  • Sunking
    Solar Fanatic
    • Feb 2010
    • 23301

    Charging or Discharging / Buying or Selling

    I see this question appear in a hundred different ways here on the Forum. People want to know if they can charge/discharge a battery at the same time, or be buying while selling if grid connected. The answer is a big fat NO silly. You can only be doing 1 of 3 things. Charging, Discharging, or Floating. It is physically impossible for it to do anything else. Just simple math and physics

    What you will be surprised with is how simple the answer is. It is 3rd grade math even Jethro Bodine with a 6th grade education can understand. It is as simple as 1 + 2 = 3 Anything electrical or electronic is pure Math. Not one bit of magic or mystery. If you can do simple addition and subtraction, you will understand what follows.

    What follows below is a diagram of an Off-Grid Battery System. However it also applies to any Grid Tied System. In your mind picture you replace the Battery with your POCO, the Charger to your GT System, and the Lamp as your Home. Makes no difference. both are identical. All you have to know is both use NODEs or a Zero Sum Point as seen and explained below.

    Note what is below is showing a fixed Load of 3 Amps. In practice the load is not fixed. I just showed it fixed to make it super simple to understand.



    EDIT NOTE:

    If trying to figure out how to use the formulas for Grid Tied use Kwh not Amps. In this case you want to see the POCO Kwh go Negative as that means you generated more than you used and receiving credit. If Positive you owe money. I know you understand money out of your pocket.
    Last edited by Sunking; 09-09-2016, 04:49 PM.
    MSEE, PE
  • Mike90250
    Moderator
    • May 2009
    • 16020

    #2
    Made into a sticky, whack-a-dooodle discussions about this will be deleted to keep the thread clean.
    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

    • Sunking
      Solar Fanatic
      • Feb 2010
      • 23301

      #3
      Originally posted by fivewin
      Diagram expl of C: ....current can flow one direction only.
      Question: Why do we need a diode, usually in the junction box of the panel??
      Diodes only allow current to flow in one directions known as rectifiers. However a Blocking Diode in a Solar Panel does not have anything to do with the example. .
      MSEE, PE

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      • Mike90250
        Moderator
        • May 2009
        • 16020

        #4
        Originally posted by fivewin
        Im only wondering if someone use a charge controller whether a diode in a solar panel is needed. Does every charge controller protect from discharge in the evenings?
        Please START a new thread asking this new question.
        This is your second attempt to hijack the charging thread. I initiated a new thread JUST FOR EWE.
        Diodes are a one way valve for electricity. They also cause a bit of loss while in use. The balance is to have enough to prevent panel shutdown, but not so much as

        please ask there,
        Last edited by Mike90250; 09-12-2016, 02:53 AM.
        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

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