Off Grid Home Forums Technical Discussion What charge controller to use?

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    Guys i need your help.I have 4 Suntech modules 280watt each.Open Circuit Voltage (Voc): 44.8 volts/Optimum Operating Voltage (Vmp): 35.2 volts/Short Circuit Current (Isc): 8.33 amps/My system is going to be 24V.I will use Studer AJ-2400 24V inverter.My question is what charge controller is suitable to handle the 35,2 volts of my array.I will proceed in parallel connection of the modules.Are the 35,2 volts a problem for a charge controller?I have in mind the Tristar 60.The controller will charge my 24V battery bank or we have an issue here?It’s my first off-grid installation and i need some of your experience.

    Waiting for your guidance…


    The best type of controller are termed MPPT which stands for maximum power point

    tracking. It will handle high open circuit voltages but remember that as soon as you apply a load the voltage drops in any case. The manufacturers spec sheet will tell you the highest open circuit voltage their device can handle but typically its in the 48- 60V range so no worries.

    Internal switch mode circuit is constantly adjusted to give optimum charge to your battery bank. Sounds like you will have a great system when assembled.


    Outback FM80’s and MX60’s are both good controllers. THey are not cheap but they will handle up to 150 vdc open circuit. They have programmable output voltages to match to about any battery.

    The FM80 are rated at 80 amps continous on the output side, MX60’s are rated at 60 amps.

    I run one array at about 100vdc in and 12 volts out feeding it with 1250 watts of PV. The second array I run at 24vd in and 12 volts out and is just under 1000 watts of PV.

    If you use these controllers read the manual closely if you feed themn with over 100VDC in cold tempertures the open circuit voltage will be higher in the winter add snow reflection, etc. One does not want to blow a $500 charge controller.


    marshall, IL

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