Proper care of MC4 connectors?

softdown
softdown Solar Expert Posts: 3,925 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
Lets say you have squirreled some panels away on a flat roof top. Production not needed during the winter so they are stored upside down. 

Is corrosion inside of the MC4 connectors likely? Should the male and female MC4 ends simply be connected to each other? Or capped off?

Upside down to avoid wear and tear when more winter time production is not at all needed. 
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • JRHill
    JRHill Registered Users Posts: 373 ✭✭✭✭
    #2
    Wouldn't an inspection answer your question?

    But since you bring it up I have two things I use. One is dielectric grease. Two is conductive grease. The conductive grease is great but my gosh ya have to be careful with it because, ah, its conductive. The 'little dab will do ya' is usually too much. The dielectric grease is just that so you can make a mess and it can complicate connections.

    But to MC4 connectors I love 'em. Very, very problem free with them over 15 years. I should probably reseat them but I do the clamp on in full sunlight under full output and the strings are identical. They were dry when I built the system.
    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #3
    My two concerns....

    https://www.staubli.com/content/dam/ecs/technical-documentation/assembly-instructions/RE/PV_SOL-LVDC-en.pdf

    MC4 connectors have something like a 100 cycle mating life... Not the worst thing in the world if you cycle once or twice a year. Just keep them clean and dry (such as plug the two ends together when installing, and again when storage)--Or just leave them plugged/installed and flip/store without unmatting.

    Second issue--I would worry that the (typically) glass top side is more UV/solar/damage resistant vs the back side (which may be some "soft" back side sheeting which may not "like" UV/Foreign objects hitting backside/animals nesting/chewing from inverted panels).

    Generally, more damage probably possible from twice a year handling vs just install and forget (or drag a "sun proof cover" over "parked/unused" panels).

    Suggest you have a 5 degree tilt (minimum) to drain water/"leaf tea"/etc. whether stored or installed. Probably don't want water to freeze during winter/cold spells (water "expanding" as ice forms, causing stress in joint/glass contact areas).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #4
    Not to mention, they will fill up with rainwater if stored upside down

    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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  • softdown
    softdown Solar Expert Posts: 3,925 ✭✭✭✭
    #5
    Oh boy. All good points. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • softdown
    softdown Solar Expert Posts: 3,925 ✭✭✭✭
    #6
    For now I have joined the male and female connectors on each panel. Stacked five high in the shade behind the existing panels. 
    With ice up there I’m in no hurry for a big project. Existing array performs superbly this time of year.

    Thanks!
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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