Connecting solar panels please help

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rayjoh
rayjoh Registered Users Posts: 1 ✭
in Solar Beginners Corner #1
hi Guys, please need some help here...
i have:
2x 12v 102ah deep cycle batteries comected im series to give 24v that is conmected to 24v ups and a 20A pwm solar panel controller.

so now I have 3x 12v solar panels 2x 80w and one 130w.

how would I connect this in series to make it 36v 290w into the pwm or in parralel to remain 12v 290w?

Thanks in advance
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  • Solray
    Solray Registered Users Posts: 246 ✭✭✭
    #2
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    Your pwm controller is a charge controller, not a solar panel controller.
    Look on the website to see the string calculator the controller manufacturer provides to find out what it is capable of.
    You will input the panels you have and it will give you the optimum configuration for them.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #3
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    PWM solar charge controllers need very specific array voltages to work (actually work and/or work efficiently).

    For PWM controllers, the array voltage (Vmp-array) should be around 17.5-18 volts Vmp. 36 Vmp-array for 24 volt battery bank and 72 volts Vmp-array for a 48 volt battery bank.

    If you feed 3x 18 Vmp panels on series (Vmp-array 54 Volts), the Watts from the third panel is pretty much wasted/lost.

    For MPPT type charge controllers, the minimum array voltage is the same as the PWM controller (realistically, should be, at least, another 5-10 volts for Vmp-array) to the maximum input voltage of the controller (typically, a 140-150 VDC input MPPT controller should have Vmp-array around 100 VDC maximum).

    An MPPT controller uses a switch mode (typically buck mode) power supply to take a wide range of input voltages and efficiently down convert to battery voltage and current.

    We need the Vmp and Imp of the three sets of panels to figure out the best mix and match for your PWM controller.

    - Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    #4
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    About all you can do with what you have is series wire the two 80 watt panels and connect them to your controller. If you can find another 130 watt panel then you can series wire them together and parallel them with the two 80's.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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