System Upgrade

PhxsunuserPhxsunuser Registered Users Posts: 4
In 2009 I bought (4) SolarWorld 175 Watt panels (44.4Voc, 35.4 Vmp, 5.3Isc, 4.9Imp, 63.4" x 31.9") and a Xantrex Model C40 Solar Charge Controller. My system is 24v. I would like to upgrade the charge controller to the Outback Power Flexmax 60 MPPT, which was suggested at the time of purchase. I am in Phoenix and would like to know if this controller will work with the summer heat or do I need to up the open circuit voltage?


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: System Upgrade

    Welcome to the forum.

    The FM60 will work in Summer; it won't be effected by the heat. The panels will, however.
    Not to worry; the usual form is to wire the four panels as two parallel strings of two in series. The array would then have a Vmp of 70.8 and an Imp of 9.8 and the controller will have no difficulty in charging your 24 Volt system even on the hottest day.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: System Upgrade

    in addition to what coot said you can use a quality mppt cc from other manufacturers too such as midnite solar's line of classics or morningstar's tristar mppt ccs. it may be to your advantage to have 2 pvs in series paralleled to 2 pvs in series to gain a bit of voltage that your summer heat would lower on the pvs.
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