2x100W solar panels in parallel issue

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rafi
rafi Registered Users Posts: 2 ✭
in Advanced Solar Electric Technical Forum #1
Hello!

I have an issue with the solar system I am trying to install in my RV. I purchased 2x100W panels from HQST and a morningstar 30 amp charge controller (with lcd screen).
I installed the solar panels in parallel to get the same 12V voltage and supposedly add the amps from both panels.

THe problem is I am getting right now with both panel a reading of about 4 amps jumping up and down of solar amp. It's not a lot and the jumping around seems weird (sun is shining 100% right now).
When i disconnect 1 panel from the pair, I get a very stable 5.2 AMPs on the screen. (both panels outputs about 5.2 amps on their own)

What could be wrong ? I dont get it  I used standard Y MC4 connectors to link them up, and i tried other Y connectors too without any changes.

Thank you!!
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #2
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    Does it read 5amps regardless of which panel you have connected?

    You did connect a battery first?  Could the battery be nearing fully charged?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • rafi
    rafi Registered Users Posts: 2 ✭
    #3
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    Yes battery is connected. Possible that the battery might be charged soon although the charging light is blinking, manual says it blinks when charging (PWM regulation), and stays on when near fully charged.

    I tried to look for the voltage input on the charge controller (full sun, winter) : with 1 panel 18.5V, with 2 in parallel 19.7
    Specs for my panel: Optimum Voltage : 18.5
    open circuit : 22.5V
    100W

     hope it helps
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #4
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    I think that explains it, I think you are just near fully charged and the battery taking less input. 19.7 is likely above your VMP so reading between VMP and VOC might indicat it switching rapidly.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #5
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    what loads are you going to run tonight?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2016 #6
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    rafi said:
    Yes battery is connected. Possible that the battery might be charged soon although the charging light is blinking, manual says it blinks when charging (PWM regulation), and stays on when near fully charged.


    I tried to look for the voltage input on the charge controller (full sun, winter) : with 1 panel 18.5V, with 2 in parallel 19.7
    Specs for my panel: Optimum Voltage : 18.5
    open circuit : 22.5V
    100W

     hope it helps


    Do you have any loads connected when you are conducting this test? 
    When you state the current is fluctuating, is the PWM % display fluctuating correspondingly ie 45% 70%? 
    Did you set the voltage with the dip switchs 2&3 or did you leave it in auto select?
    Most importantly did you connect the battery first, let the start sequence GYR led's flash one by one, before connecting solar?

    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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