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my system doesn’t preform as calculated

Asked by: 1775 views Solar Installation

I have a system I installed to run a Whirlpool chest freezer rated at 354 kwh/yr.  My system has two Sun-190 arrays in parallel going into a C-60 Xantrex charge controller which connectes to three 12v lead acid batteries (marine deep cycle) then into a Chicago Electric 5000w inverter rated at 12-15vdc in for 110vac out.

I calculated 30 kwh/mo in Little Rock, AR to give 3.88 sun-hr requiring solar panel wattage of 335 watts. The two Sun-190s give 380.  With 380 watt of solar power and 3 days back up for cloudy days and min battery temp of 25 degrees, I calculate 3 12v batteries of 125 amp-hr to require 3 batteries in parallel giving 330 amp-hr.  However, the system will not run over night without shutting down at the inverter.  I’d like your assessment.

1 Answers

  1. avatar Sam says:
    November 5, 2011 at 1:41 am

    OK you are going to loose a percentage of power gained because C-60 is not a MPPT charger
    any inverter is not 100% efficient
    you will never get out what you put into a battery
    you have three battery’s in parallel that can’t equalize (never more than two).
    Batteries are very inefficient at that temperature (you want 70 degrees)
    you want to only discharge batteries to 80% capacity for long life
    I would add one more panel and replace your batteries with two huge 6 volt batteries
    Marine batteries are not true deep cycle batteries


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