In series or parrellel

CarkCark Registered Users Posts: 10 ✭✭
I have 4 250 watt HES panels and a Xantrex C60 Charge controller. Should I run two strings in series or 1 string of 4 in parrellel. Batteries are Interstate UL16.
Clark

Comments

  • littleharbor2littleharbor2 Solar Expert Posts: 1,626 ✭✭✭✭
    Need specs for your panels. 250 watt sounds like 60 cell panels. You would need an MPPT controller to use 60 cell panels for battery charging. The C-60 is a PWM controller.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Also need to know the configuration of your battery bank (12/24/48 volt) as well as the panel specifications as LittleHarbor2 asked.

    And, in general, a PWM type charge controller (like the Xantrex C60) is not a good match for >~140 Watt solar panels.

    Typically 140 watt and less panels are 36 cell panels with Vmp~18 volts... A good match for 12 volt battery banks. Vmp-array->12 volt battery bank works fine with a PWM charge controller. A Vmp-array~36 volts, works well with a 24 volt battery bank.

    Most >140 Watt panels are either 60 or 72 cell panels with Vmp~30 or 36 volts. A Vmp~30 volt panel is too high of voltage to efficiently  (something near 50% efficiency) charge a 12 volt batter bank and too low of voltage to properly charge a 24 volt batter bank using a PWM charge controller.

    If you have a (more expensive) MPPT type charge controller (maximum power point tracking), you can put a Vmp~30 to ~100 VDC array through a MPPT controller and efficiently (95%) charge a 12 volt battery bank. (Vmp-array > 35 volts to charge a 24 volt battery bank).

    Of course, there are many types of charge controllers out there (PWM and MPPT)--Need to check the specifications for "your" charge controller to make sure everything matches.

    And, we always suggest making a paper design of your system first... Pick the hardware that meets your design needs (and budget), before you buy any hardware. It is easy to end up with stuff that does not play well together or meet your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CarkCark Registered Users Posts: 10 ✭✭
    Panels are 60 cell, battery bank is 4 6 volt in series for 24 volts.
  • littleharbor2littleharbor2 Solar Expert Posts: 1,626 ✭✭✭✭
    You need an MPPT controller and need to wire your panels in series to increase your voltage. The 30 volt Vmp output of your panels isn't high enough to charge and equalize your 24 volt battery. In hot weather the output voltage of your panels will drop too low to properly charge your batteries.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • CarkCark Registered Users Posts: 10 ✭✭
    Thanks, Clark
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