can anyone tell me what these are called? our how to connect them?

ronjambo
ronjambo Registered Users Posts: 5 ✭
in Solar Beginners Corner #1
Attachment not found.

If you cant see the image here, it is the same as my profile pic. The metal strips coming out of the back of my solar panel.

Mike
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: can anyone tell me what these are called? our how to connect them?

    Looks like they forgot to mount the junction box etc. An unfinished product. Weird.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: can anyone tell me what these are called? our how to connect them?

    Welcome to the forum Mike.

    What you have there is a panel that has no junction box on it. This is not good. Those tabs are called "tabs" and they are the "raw connection" to the cells of the panel.

    They are probably the (-) "junction" and (+) tabs, meaning they are meant to have the bypass diodes connected across them as well as the positive and negative leads in the right place.

    You should be able to determine which is what with a bit of light on the panel and a digital multimeter to check the polarity and Voltages on the tabs relative to each other. Label them 'A' 'B' 'C' and use the meter to measure A to B, A to C, and B to C noting both Voltage and polarity, i.e.: "A to B is +8 Volts, A to C is +16 Volts, B to C is +8 Volts" or something like that.

    Then you may need to search around a bit to find some junction boxes you can glue on, but the bypass diodes and leads are not so difficult to come by. Soldering the tabs can be an adventure, though.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #4
    Re: can anyone tell me what these are called? our how to connect them?

    They are the copper bus tape (not sure exact term) from the solar panel. Search eBay for solar panel junction box.

    You can search on Google for instructions (and videos) on how to connect j-boxes to the back of the solar panel.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ronjambo
    ronjambo Registered Users Posts: 5 ✭
    #5
    Re: can anyone tell me what these are called? our how to connect them?

    OK
    That helps a lot. I have a junction box but it seems most of the videos are about how to connect mc4 chords and the like to them but not so much about how to connect the box itself. I guess I will try to get a voltometer tomorrow and go from there.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #6
    Re: can anyone tell me what these are called? our how to connect them?

    This video shows using silicon caulk to glue down the box, and the terminals on this unit are spring loaded contacts... Others may need soldering or spot welding.

    http://www.youtube.com/watch?v=rZTqNgtOEwk (part 5/5 on repairing a panel--4 terminal array--yours is a 3 terminal array output).

    There are neutral cure silicon seals (I would recommend this--such as GE Silicon II) and other types such as Acetoxy which release acetic acid type silicon caulks (I would not want that near electrical connections).

    Again, just my personal opinion. Otherwise, you probably would have to do some more research on two part silicon/adhesives for this type of job.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ronjambo
    ronjambo Registered Users Posts: 5 ✭
    #7
    Re: can anyone tell me what these are called? our how to connect them?

    Attachment not found.

    Here is the box. Great video but I have one question: His panel had 4 bus wires and I have 3. I am guessing the middle one is a ground? do I just put it in EITHER middle clamp/hole? or do I need to buy a new junction box? Seriously thankyou for finding that video

    Mike
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #8
    Re: can anyone tell me what these are called? our how to connect them?
    ronjambo wrote: »

    Here is the box. I guess they just slip in the big hole. Left in the far left, right in the far right and middle in either slot?

    The J-box that you show in the picture is designed for use with a panel composed of three separate segments instead of two. That is, one with four pieces of bus/tabbing wire coming out instead of the three that yours has.

    You could just connect to either of the two central holes, but if you do that one portion of the panel will have two bypass diodes in series, for a larger voltage drop on a shaded panel. That is not really significant in most cases, but you can avoid it by joining the two central terminals with a short jumper wire and then connecting the bus wire to either of them.
    SMA SB 3000, old BP panels.
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  • stevehull
    stevehull Registered Users Posts: 20 ✭
    #9
    Re: can anyone tell me what these are called? our how to connect them?

    Do all junction boxes (on the back of a PV panel) have a blocking diode?
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  • ronjambo
    ronjambo Registered Users Posts: 5 ✭
    #10
    Re: can anyone tell me what these are called? our how to connect them?

    so the "lock" on my j-boxlooks different from the one in the video. How essential is it for me to get it right? If I solder the tabs in they should work fine right? Along with the jump wire inetdog was talking about? then fill it all in with silicon? Sounds like a plan forming. could I check the wires coming out in the direction of the batteries with a voltmeter to make sure it works before I glue it on and insulate it? Rank amateur here.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #11
    Re: can anyone tell me what these are called? our how to connect them?

    Those are not blocking diodes, they are bypass diodes. Basically if some solar cells become blocked due to shading--They go high resistance. For every ~12 volts of cells (~24 cells in series), there is a diode wired in "reverse". If the cell is shaded, it goes "high resistance" and the bypass diode will then short the current around the shaded cells.

    If you can solder the tabs, that should be OK too (you might need a larger soldering iron to do that).

    Regarding the mounting of the J-Box--I am not in the business, so what you see is what I know.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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