MNPV6 combiner ,150v dc polarity sensitive breakers.

[offgridQLD]

I have been trying to narrow down a nice combiner box for a new array install. The system is 12 x 200w panels  divided into 6 x  2S / 1 P configuration.  So I was looking at the MNPV6 combiner and 6 of the 150v DC beakers.

My issue is that breakers in Australian by code in PV installations can not be polarity sensitive . Are the midnite breakers still polarity sensitive?

Given that I also need a main PV disconnect / isolation switch at the panels (as my PV disconnect at the other end is more than 3m distance from my roof panels so I require a 2nd one up on the roof to met code) Because of this need I was also looking at the combiner boxes like the MNPV6-Disco Combiner to kill two birds with one stone.

Though if I cant use the midnite 150v breakers due to the polarity sensitivity issue (this might not be a issue if you have a new line of breakers that are not polarity sensitive) I know I could use fuses but is there a disconnect enclosure that will take 6 fuses and get the same job done perhaps with a switched fuse holder?  I can only hold 4 in the MNPV6 enclosure .

Just some advise on what product you have to get the job done.

Kurt

[Halfcrazy]

Kurt
That is a tough one. At the present time the Din rail breakers are still polarity sensitive. One thing that can be used is the MNPV6HV-Disco it uses fuses and has a load break rated switch.

Ryan

[zoneblue]

Same thing happening in NZ, from next year, must not be polarity sensitive. I hope you guys are talking nicely to your breaker maker... it will be a real bummer not to have a din dc breaker.

[Westbranch]

seem to recall another posting on this, may have been about polarized breakers as we have now.
I think it was Robin.
http://midniteforum.com/index.php?topic=443.msg2612#msg2612

[offgridQLD]

Thats ok,
              Thinking about it more I will go with the MN-MNPV12 that can hold 10 switched fuses.

I can use 6 of them for the 12 panels - 2400w  discussed. I also have another 8 panels - 1600w that will be installed  on the roof behind this array once I get the tilt frame sorted for them. So space fot I 4 more fuses will be perfect.

As for the main isolator within 3m of the panels I will just install one in a separate enclosure I think this will be the simplest way.

kurt

[Halfcrazy]

Fuses are not switched. Be very very careful. Do not ever open them under a load they can and will catch on fire. We are definitely working diligently towards non polarized breakers one way or the other.

Ryan

[offgridQLD]

Thanks for the warning. I guess a second main isolation switch on the out feed of the combiner box . Remove load first then go at the fuse. Though the breakers would be much nicer especially when wanting to quickly single out strings for testing and not having to carry fuses on hand or fiddle around  changing them in the dark should a issue come about .

I really like the mid nite combiner boxes though. Perhaps I due to my situation I can try and hunt down another brand of non polarity sensitive dc breakers.

Are the mid nite breakers just standard din rail sizing (or are the midnight breakers a 1/2 size or thin width) ?

Kurt.

[phonetic]

Standard DIN MCB are 18mm wide, Midnite DC breakers for combiner box 12mm wide.