PV inverter and MPPT feeding from same PV array?

Can I connect a PV Inverter from the same PV Array of my MPPT Charge Controller to take advantage of the full potencial of the PV array when the battery are charged by the MPPT?
I have a MX60 charging 8 Trojan batteries with 4 x 250 Watts panels but when the batteries are full the MX60 goes sleeping and I waste the rest of the energy in that day. so I'm thinking to install a Enphase M250 to each panel to AC couple to the output of my Inverter/charger.

This way I do not use the reserve from my batteries just the exceed of my PV array.

Theoretically it does not have anything in common because the inverter connected to the batteries has a magnetic bond to the AC output and the PV inverter will have a AC Coupling will not notice that...
Am I right?

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭

    I guess you plan to split the out put cables? Sounds "Wacko"

    Generally a charge controller will draw current from the array once in float to maintain the float voltage. So just save your money!

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    If you do not want to WASTE some of the PV  production in an OFF GRID system, the only way to do it i to turn something ON
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • vtmapsvtmaps Solar Expert Posts: 3,739 ✭✭✭✭
    Your scheme won't work, but your desire to capture the unharvested, potential energy makes sense.  There are several ways to do it, but most of them work best with a resistive load... the amount of "wasted" energy changes minute by minute.

    You can accomplish your goal with another controller used as a dump controller.  Set your MX to charge at 0.2 volts higher than the dump controller.  The MX will put out all it can to raise the voltage above what the dump controller allows.  The dump controller is where you set your desired absorb and float voltage. 

    The Midnite Classic controller has a sophisticated feature called "waste not"... an auxiliary output that can control an SCR.  You can read lots about it on the Midnite website and their forum.

    --vtMaps


    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭

    What does that accomplish vtMaps? He's not talking about running a specific load only when the charge controller is in float.

    To use the energy from the array all he needs to do is run loads, or as Westbrach said, "turn something ON".

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,028 ✭✭✭✭✭
    Almost any charge controllers can Aux control a load. Your scheme does sound weird to me because of what others have said.
    Your goal is a good one and I think I have tried them all. At this point in my offgrid life I think the mini-split heat pump is the best way to use excess energy. I have given up on AUX relays and do this all with wifi directly controlling the load for my clients.

     You really have to also keep in mind that all of this excess capacity off grid will be needed in six months or so when
    when the sun is not so high in the sky. It is this balance (off too much and too little) that you just have to accept. It is also the principal I use for many of my clients who choose not to run a generator.

    You said the MX-60 is sleeping, it is floating really is it not?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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