Controller / panel compatibility question

I am installing 2 LG360Q1C-A5 panels in paralell... the current controller is a xantrax C40 pwm.  Will this controller be compatible?


  • BB.BB. Super Moderators, Administrators Posts: 32,601 admin
    What is your battery bank voltage?

    If your battery bank is 24 volts, then the LG panel specifications are a good/efficient match:

    • MPP Voltage (Vmpp) = 36.5 Volts
    • MPP Current (Impp) = 9.87 Amps
    Power wise:
    • 40 amps * 36.5 volts = 1,460 Watts from solar array
    • 40 amp controller / 9.87 Amps Imp = ~4.1 panels = 4 LG panels maximum in parallel
    Check the owner's manual... Many times there are deratings and you may, for example, only be "allowed" to put 3x LG panels on the controller (NEC deratings, etc.). You do not want to exceed the controller's maximum current rating. (MPPT type charge controllers--A completely different story).

    If you have a 12 volt battery bank, the controller will work fine (PWM--Pulse Width Modulated) but the Vmp~36.5 volts will be too high--And you will only "use" about 1/2 of the solar panel Wattage.

    For a 12 volt battery bank, you want Vmp=~17.5 to 18.5 VDC to "match" the 12 volt battery charging voltage.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rdm3rdm3 Registered Users Posts: 6 ✭✭
    Thank you Bill!  I have ordered a Renogy 60A MPPT... got a great price - problem solved. I will have all the power I need with room to expand.  I very much appreciate your wise counsel and research.
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