Best option Kyocera 135 Junction Box or MC4 Cable?

Truth MachineTruth Machine Registered Users Posts: 9
Folks I am going to start my PV purchase and I've decided to go with the Kyocera 135Watt PV.

My question is, what is the real difference, if there is any between the KD 135SX-UPU with a junction box or the KD135GX the uses a standard MC4 Extention cable.

Do you experts have a opinion on the junction box or MC4 cable being the best unit/PV setup for the long term use. Or, does it even matter.

The GX model is about $60 dollars cheaper than the SX but that is not an issue. I just want the best setup and ease of hook-up, quality of components longterm, etc.

thank you

Feedback please

Comments

  • SCharlesSCharles Solar Expert Posts: 123 ✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    I have the Kyocera 130s [virtually the same as your proposed 135s] with the junction box. I was adding nine of them to an existing array, composed of three other brands of panels added over the yr.

    I opted for the simple junction box, too, as all my other panels were of that style. As you said, a bit less expensive and I didn't need any special connectors, just wire and crimp connectors.

    I am perfectly happy with them and will buy the same style, should I decide to add to the array once again. Save the money. It will take you a few minutes more per panel to connect the wiring, since you have to crimp each connector. Oh, and you'll have to carry the crimp tool along in your back pocket. No big deal.

    As to longevity, my first array went up in 1985 and the connections are still great. No big deal.
  • Truth MachineTruth Machine Registered Users Posts: 9
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    SCharles,

    thanks so much for the reply. Just so I understand, is the junction box a newer component to the PV or is the MC4 Cable the newer component. And to make sure we are addressing the same PV, the junction box version of the Kyocera is the more expensive model of the two.

    Sorry if these questions seem dumb, I'm just getting up to speed on solar so I'll have many more dumb questions to ask over time.

    thanks
  • SCharlesSCharles Solar Expert Posts: 123 ✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    The junction box is the older version. The version with a post to which you attach the wire with a crimp on [or solder on] connector. The MC4 version requires use of a cable which one simply pushes on to the receiver.

    I was unaware that the junction box type was more expensive now. When I last bought panels, in 2006, the junction box versions of various brands of panels were either less expensive or the same price as the MC4 versions. The place I bought the panels asked me which version of the panels I wanted and said that contractors preferred the MC4 version as it was faster to install and hook up. Plus, they were less likely to end with an inadequate connection due to a poor crimp. I chose the junction box because I didn't want to buy the MC4 cables, which are more expensive than taking some wire and crimping on a connector. Plus, as I said, all my other panels were junction type and I was happy with them, they'd worked great all those years and still do.

    If the connection options are now the same price, it is up to you whether you want to purchase the cables or make your own. I suppose that if the MC4 panels are cheaper, the savings might well pay the cost of the MC4 cables.....

    By the way, I am "just" a homeowner who built my own place by myself, including all the PV system. So, I am not a professional installer. There are surely to be some pro's on this forum and no doubt someone will jump in here and perhaps know some reasons to go with the MC4 I don't know about. All I know is, mine have worked perfectly for many years.
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    The junction box is an "older" style (in general). The locking MC4 (and equivalent) is current technology that supports quicker/less expensive installs using crimp and plug type connectors (NEC national electrical code requires "locking" connectors on Grid Tied systems, or junction boxes with screws, to reduce the chance of somebody popping open a plug and shocking themselves).

    I lean towards using MC4 connectors vs a junction box. J-Boxes are pretty difficult to seal against weather (even well sealed boxes tend to sweat from tiny water leaks--moisture drawn in by differential pressure and temperature). Pigtail versions of solar panels should have less of an issue (more reliable).

    Although, my pigtailed solar panels failed at the sealed junction box (probably not water intrusion) after ~5 years (being replaced under warranty)--So nothing is for sure.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Truth MachineTruth Machine Registered Users Posts: 9
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    Charles and BB thank you so much for the replies. Very helpful.

    thank you
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    By the way, you can avoid the MC4 crimping by purchasing pre-made Male/Female MC4 cable sets. Just cut in 1/2 and terminate the cut ends into the rest of your wiring.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?
    Folks I am going to start my PV purchase and I've decided to go with the Kyocera 135Watt PV.

    My question is, what is the real difference, if there is any between the KD 135SX-UPU with a junction box or the KD135GX the uses a standard MC4 Extention cable.

    Do you experts have a opinion on the junction box or MC4 cable being the best unit/PV setup for the long term use. Or, does it even matter.

    The GX model is about $60 dollars cheaper than the SX but that is not an issue. I just want the best setup and ease of hook-up, quality of components longterm, etc.

    thank you

    Feedback please

    Is this for a grid-tie or off-grid setup?

    Grid tie setups normally connect a bunch of panels in series and that is MUCH easier and cheaper with MC4 connectors. Basically one panel just plugs into the next and then one set of MC4 pigtails at the end.
    Unless you use enphase micro inverters, in which case you have to go with MC4 since the MC4 connectors plug right into the micro inverter. Well you could go with MC3s but why?
    However since you've settled on 135 watt panels, I'm guessing your not going with micro inverters.

    If it's for an off grid where the panels are mostly in series, the junction boxes might be a little easier. But it's still cheaper to go with MC4s if the junction box panels are as expensive as you say.
  • Truth MachineTruth Machine Registered Users Posts: 9
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    Peter V, thanks for chiming in. I'm basically looking at an off grid setup that has quality components and the ability to expand further over time, ie., more PV's and more battery's as money permits.

    I suppose it will be classified as a grid tied system because it will have all the standard equipment such as a charge control, invertor, and battery bank.

    I'll probably get some criticism because my plan's are a little unrefined at this point.

    thanks for all the help.
  • SlappySlappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    I'll probably get some criticism because my plan's are a little unrefined at this point. no, know one should do that, every body has to start some where, their is a a lot of smart people here, they will try to guide you in the right direction, because they have been their and done that. But what worked for me is did a lot of reading in this forum, and was over whelmed with all the info until my head turned to mush. so I just took the plunge and ordered 4 k.c. 130's just to see what I can do with them,(hands on approach) as in powering my needs. its has been a little over a year now, and learned a heck of a lot with running different things and for how long in different weather conditions, (doing this before taking the plunge to go off grid). Just ordered 4 more k.c. 135's (all 8 is junction box) and it will do my needs just well (hopefully). and the junction box type panels will give you the option to change your panels around from parallel to series wiring for different voltage set ups with out ordering new cable...........one thing I did learn, is, you will be surprised on how quick 2 ceiling fans will pull down a battery.;)

    I suppose it will be classified as a grid tied system because it will have all the standard equipment such as a charge control, invertor, and battery bank. if it is not hooked or tied into a electric company, it is an off-grid.
  • petertearaipetertearai Solar Expert Posts: 408 ✭✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    I have used both types. The pb panels have junction boxes. The Sharps have leads.
    The ones with leads are quicker and easier to install. Both are ok so far from a reliability point of view.
    You have found a great forum to ask questions.
    Regards Peter
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . victron battery monitor . 24 volts 450 ah surette batterys . off grid  holiday home 
  • Truth MachineTruth Machine Registered Users Posts: 9
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    Thanks folks for all the inputs. This really is a great place to learn and discuss.
  • System2System2 Posts: 6,290 admin
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    Just did this decision, replacing a damaged older Kyocera130. :cry: I like the mechanical aspect of the older Jbox-a lot of advantages in my opinion but I would suggest going with the MC leads style. Though its just a potted box with leads. Why?

    Neither paying the extra for older Jbox nor switching or modifying existing cables to new multicontact leads was an option because money was a consideration-just wasn’t in the budget. I opted to order newer style because it was cheaper as you noted, salvaged Jbox off old panel and installed on new panel. Cut off connectors and hooked up to old box, now I can connect my existing leads so Im not spending anything on rewiring. (ya warranty is gone)

    I only offer this as a 'down the road' because you don’t want having to make the decision again...or mine.
  • creakndalecreakndale Solar Expert Posts: 27
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    In theory, the smaller footprint of the MC4 type mechanism allows the cell above to run closer to the temperature of the other cells. By having a large, J-box attached to the back side of a cell's location, that cell would run slightly hotter since air circulation is blocked.

    creakndale
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    This is one case where theory and baloney probably have a lot in common.

    The air flow it blocks will be significant? I doubt it.
  • System2System2 Posts: 6,290 admin
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    creakndale/russ think your both right. The mounted box may cause a temperture differanc between where box is mounted and other cells- however the footprint between the older M style Jbox and the MC box on Kyocera panel is minimal. roughly 5x4 vs 4x4 so dont think youd see the differance between box styles as far as temperture.

    When I added the Jbox to my MC panel I brefly thought of glueing to back side but decided to mount to frame. Covering another cell (heating) didnt occur to me though, just easier.
  • 2manytoyz2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    When I bought my first 130W Kyocera panel, I went with the simple junction box. Easy to tie it into my basic setup of panels in parallel. I added another three Kyocera 130W panels.

    I went to buy another two recently, only to discover this model is now discontinued. I've since purchased two Kyocera 135W panels. These have a similar junction box as the previous model. They do include a couple of watertight fittings now. Had to buy those separately in the past.

    dscn6056.jpg

    dscn6057.jpg

    dscn6058.jpg

    Since I'm not daisychaining the panels, I prefer the junction boxes. Don't think you can go wrong with either setup. Good quality hardware.
  • petertearaipetertearai Solar Expert Posts: 408 ✭✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    hi looking at your photo , is the gland designed for 2 separate cables or a compensate 2 core cable?
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . victron battery monitor . 24 volts 450 ah surette batterys . off grid  holiday home 
  • 2manytoyz2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?
    hi looking at your photo , is the gland designed for 2 separate cables or a compensate 2 core cable?

    It appears to be designed for one cable, but the material is soft & pliable. It had no problem sealing tightly against both wires.

    I had a tube of clear 100% silicone standing by, but was satisfied with the seal.
  • petertearaipetertearai Solar Expert Posts: 408 ✭✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    Very clear photos! I would try to make sure the cable are arranged in such a way that any water doesn't run down to the gland.Should be ok as the panel will hopefully keep it water tight.
    Regards Peter
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . victron battery monitor . 24 volts 450 ah surette batterys . off grid  holiday home 
  • SCharlesSCharles Solar Expert Posts: 123 ✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    I did not use mine, as the 8 ga. wire I use won't go through, doubled; or, I could not seem to get it through.
  • 2manytoyz2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?
    Very clear photos! I would try to make sure the cable are arranged in such a way that any water doesn't run down to the gland.Should be ok as the panel will hopefully keep it water tight.
    Regards Peter

    Camera is nothing fancy, but the macro function works well!

    In my application, the junction box ends up being a few inches off the roof, and the cable lays in such a way that the water will roll off the cable, rather than direct it upwards towards the gland. Rain is a constant threat here in FL. Snow... not so much. ;)
  • 2manytoyz2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?
    SCharles wrote: »
    I did not use mine, as the 8 ga. wire I use won't go through, doubled; or, I could not seem to get it through.

    I'm only using 10 gauge wire from the panel. It's a short run (~25'). 8 Amp panel, 12V, 25' = 10 ga for a 3% loss.

    http://www.freesunpower.com/wire_calc.php

    Not sure if you could get a different gland insert, or modify the existing. Might be able to remove some material with a soldering iron (smelly project). I have access to LN2, and a lathe. :p
  • JESSICAJESSICA Solar Expert Posts: 289 ✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    I have 6 Kyoceras 130, with junction box (I paid more than $600 each; now you can buy them for almost half that!)
    They were installed 4 years ago, in my house in Puerto Rico: Lots and lots of rain. So far, no problems at all;

    Now, one question: With the newer mc4 connectors, how does one connect two or more strings in parallel?
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?

    Two strings in parallel:

    wind-sun_2155_1540495Multibranch MC4 Connectors, Latching
    Price: $26.00

    (Both sexes are available)

    If more than two strings, you really need a combiner box +fuses/breakers for safety (and a return isolated bus bar in the box).

    More than two panels/strings in parallel, a short at one panel can have too much current supplied by the other panels in the parallel connected strings if there is no fuse/breaker per string.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?
    2manytoyz wrote: »
    I'm only using 10 gauge wire from the panel. It's a short run (~25'). 8 Amp panel, 12V, 25' = 10 ga for a 3% loss.

    http://www.freesunpower.com/wire_calc.php

    sidenote here-

    for a 25ft run of #10 at 8a and 68 degrees f (too low in temp as wires will be much hotter and should be rated for 194 degrees f by nec standards) you will get a 3 and 1/3% vdrop. at nec standards of 194 degrees f (90 degrees c) that voltage drop is 4.25%. #8 at that length would give a 2.67% vdrop for 194 degrees f. even just changing over 1 of the wires, either the + or the -, to #8 will not bring it below 3% as it would be 3.46% at 194 degrees f. you cannot ignore the heat in the wires as that adds more resistance to the wires. you cannot assume just ambient air temp either as the current going through the wires will dissipate heat due to wire resistance and as i said higher heat equals higher resistance.

    these calculations i just ran are accurate and can be done on the voltage drop calc in my signature line.
  • JESSICAJESSICA Solar Expert Posts: 289 ✭✭
    Re: Best option Kyocera 135 Junction Box or MC4 Cable?
    BB. wrote: »
    Two strings in parallel:

    wind-sun_2155_1540495Multibranch MC4 Connectors, Latching
    Price: $26.00

    (Both sexes are available)

    If more than two strings, you really need a combiner box +fuses/breakers for safety (and a return isolated bus bar in the box).

    More than two panels/strings in parallel, a short at one panel can have too much current supplied by the other panels in the parallel connected strings if there is no fuse/breaker per string.

    -Bill

    Thanks, Bill.

    Then, in my opinion, for systems with two or more panels/strings in parallel, junction box panels, though initially a little bit more expensive, will at the end be the less expensive option, given the high cost of all those connectors, etc.
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