connect two 48v inverters to 96v battery bank

duradadurada Registered Users Posts: 1
Is it possible connect two Cotek SP4000-148 4000 Watt 48 Volt Pure Sine Wave Inverters to 96 v battery bank separated to two parts (4 batteries for each inverter) and then connect output 110 v from both inverters together for double output power? Look Please diagramm. I will very appreciate for any suggestions. 


Comments

  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    In order to double output with two inverters combined, the inverters generally need to be designed to do so.  I don't think these inverters are designed to do this.

    Are you sure the charge controller is for a 96v bank?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Super Moderators, Administrators Posts: 31,156 admin
    In general, pulling power from 1/2 a bank of batteries is not a good idea. You want all of the batteries to share the same charging/discharging current. When you draw from 1/2 a bank, one side is going to be more discharged than the other--And with the charger connected to 96 volts overall, you need to "balance" the two banks.

    While it is certainly possible to manually balance the banks, and there is even hardware that can automatically balance the high/low banks (basically bi-directional isolated DC to DC converter--It will take current from the "high voltage" bank and pass it to the "low voltage" bank. These converters are available, but generally just for 12/24 volt battery banks (like an RV with 24 volt chassis battery and 12 volt house battery bus).

    I have not seen a 48/96 VDC battery bus balancer, but they may be out there (I am not in the solar/battery biz).

    The standard solution would be to make one "big" 48 VDC battery bank and run the solar array and AC inverters as 48 volts (all connected in  parallel to the 48 VDC bank).

    There is not much of a reason that I can think of for splitting a 96 volt battery bank as you proposed. (yes, higher battery bus voltage, is lower battery bus current--But 8,000 Watts on a 48 volt battery bank is quite doable--Roughly 140 Amps nominal current).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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