Synchronising two Charge controllers

huntep
huntep Registered Users Posts: 9 ✭✭
Just added a second XW MPPT 60-150 charge controller with 7 X 210W evergreen panels and generated an input over voltage fault.
After removing one panel the fault disappeared. Now the system is balanced, 6panels on one array and 6 on the other. However, the second SCC puts out 50W say while the first SCC puts out 500W. If the first array is disconnected, then the second SCC puts out 500W. If the second array is disconnected the first SCC puts out ~600W. My question, how do I balance the two? BTW the SCC02 program copied from SCC01.
Both connected to the same battery bank 24V 1200AH. Inverter XW4024. The arrays have same orientation. Thanks.

Comments

  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    Re: Synchronising two Charge controllers

    My system works like this: When the chargers are in bulk, they supply what is needed by the battery plus the loads equally. This is because bulk is a constant current mode. When the system transitions to absorb, then the first controller will supply what is needed for absorb current plus the loads. In order to get both charge controllers on line at the same time, you have to have enough loads. Since absorb mode is a constant voltage mode, once the battery voltage rises to the absorb voltage, then the system will unload. The way I keep mine going is to use a dump load. Once the system gets into absorb mode, I switch in a 45 amp heating element. If your PV harvest exceeds your demands, then the system will stay in absorb mode. If there are clouds going by, then the system voltage begins to drop and the chargers will go into bulk mode. If you have no diversion loads, then when your batteries are fully charged, you only harvest as much from the PV as your loads require.

    Joe
  • huntep
    huntep Registered Users Posts: 9 ✭✭
    Re: Synchronising two Charge controllers

    Thanks Joe, for your reply. After resetting the SCC02 controller to fectory defaults and re-copying the config from SCC01 yesterday, I found them to equalize much more. I also tightened the MC4 connectors on the panels a bit more and as the sun came up this morning both controllers were harvesting approximately the same.
    Now my question is, when the batteries are full will the excess power flow to the Grid to turn the meter backward? or will the controllers just shut down? I notice that the inverter (XW4024 hybrid) is always using about ~30% of the current load power from the grid. My grid support voltage set to 25.3V.Thanks
  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    Re: Synchronising two Charge controllers

    Your inverter will begin to push power back onto the grid if SELL is enabled and the battery voltage is "above" the grid support volts.
  • huntep
    huntep Registered Users Posts: 9 ✭✭
    Re: Synchronising two Charge controllers

    I think i'm missing something... My manual for the XW series Hybrid 4024 mentions all that, but only gives examples for the XW6048 inverter... where do I find the sell parameters in the programming?
  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    Re: Synchronising two Charge controllers
    huntep wrote: »
    I think i'm missing something... My manual for the XW series Hybrid 4024 mentions all that, but only gives examples for the XW6048 inverter... where do I find the sell parameters in the programming?

    Sell depends on what the battery voltage is and the grid support voltage setting (assuming sell is enabled).

    If you want to convert the numbers from a 48 volt system to a 24 volt one then divide by 2.

    You are getting into the area of X firmware that is somewhat nebulous. I dont even think the tech support guys know how it works.

    See figure 3-8 in the manual on page 3-25 the explanation in that figure is close but there is also a hysteresis value associated with grid support volts. According to Schneider techs, the GSV has a hysteresis of +.3 volts and -.7 volts and that is just about what I see with my system. This variability of the setting makes determination of exact levels of sell and grid support very hard to pin down.

    Although I dont sell, I have had to determine my system settings by trial and error. I can list out the pertinent ones to get you in the ballpark but you will have to fine tune the numbers for your particular circumstances.
  • huntep
    huntep Registered Users Posts: 9 ✭✭
    Re: Synchronising two Charge controllers

    I think I narrowed down the parameters for doing a reasonable balance between drawing from the Grid and my battery bank. However, I still have a few concerns about the difference in the controllers. I notice that the #1 SCC has Ver. 1.05 Build 0003 and the #2 SCC has Ver. 1.06 Build 0006. The first controller always seem to be putting out while the second is either tending to low light conditions or going to absorption when #1 is still in Bulk. I've been reading that V.1.05 is very stable, could it be that V. 1.06 is not? Thanks...
  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    Re: Synchronising two Charge controllers

    First of all, I would make sure that both of them had the same rev of firmware.

    ETA both of mine have 1.05.00 BN6 I am not aware of a 1.06 version and I was told by Schneider a few months ago that this was the most up to date firmware (my surprised look)