I got myself two NOARK Ex9BP-JX DC 2P MCB's for some rewiring over the December time period. I just want to confirm that I can use these between my Panels and MPPT PV Input and between my MPPT Battery Output and Battery.

The MPPT is 150V.

This diagram shows the 2P wiring. Can I safely use it like that? I've seen DC MCB's wired incorrectly on youtube and don't want to become a statistic.

and

 

Other NOARK documentation has the + and - swapped around like below:

My breaker looks like this:

 

 

Morning you need to be careful wiring up DC breakers so that the magnetic field directs the DC spark into the catch cage. If the source is your PV you can bring the wire into the CB either at the top or at the bottom like an isolator but then you must be consistent and ignore the + and - on the other side. Your current flow between MPPT and battery is usually  bi-directional and DC circuit breakers  are not designed for bi-directional use.

The Amps you are going to draw from your battery is could  exceed what a DC breaker is able to switch. So I would recommend you have a DC breaker between PV and MPPT and a battery disconnect between battery and MPPT. You don't mention what size you PV array is and whether the array is made up of several strings or the size of your inverter. So my recommendation is made with incomplete facts.

https://www.youtube.com/watch?v=Cup5fMGaE2g

 

Edited November 27, 20205 yr by Chris Hobson

8 minutes ago, Chris Hobson said:

Morning you need to be careful wiring up DC breakers so that the magnetic field directs the DC spark into the catch cage. If the source is your PV you can bring the wire into the CB either at the top or at the bottom like an isolator but then you must be consistent and ignore the + and - on the other side. You wiring between MPPT and battery is usually  bi-directional and DC circuit breakers  are not designed for bi-directional use.

The Amps you are going to draw from your battery is could  exceed what a DC breaker is able to switch. So I would recommend you have a DC breaker between PV and MPPT and a battery disconnect between battery and MPPT. You don't mention what size you PV array is and whether the array is made up of several strings or the size of your inverter. So my recommendation is made with incomplete facts.

https://www.youtube.com/watch?v=Cup5fMGaE2g

 

Sorry for the incomplete information. The array is small, it's 1000W (5S/2P) of 10 100W 36Cell panels rated at  <12A Isc in total for the 2P combination. The Battery DC breaker is 40A as the MPPT is a 150/35. I've only shown the PV breaker for illustrative purposes to indicate the polarity markings.

My concerns was that magnetic direction with the two conflicting sets of information from NOARK.

Use the direction of current flow into the switch i.e. the source side (PV in this case). You understand why you cannot use a DC CB between MPPT and batteries as sometimes the MPPT is the source and sometimes the batteries are the source. If you have a separate set of wires directly from the battery to load then you can have a CB between MPPT and batteries but then you need a CB/battery disconnect on the load cables depending on the maximum possible draw. I think you have a Victron MPPT. Some Victron MPPTs have terminals for load and others do not.

I would be inclined to have a DC CB between PV and MPPT and a battery disconnect between batteries and load. A second DC CB would be superfluous between MPPT and batteries. Just make sure your cables are specced properly. 

27 minutes ago, Chris Hobson said:

Use the direction of current flow into the switch i.e. the source side (PV in this case). You understand why you cannot use a DC CB between MPPT and batteries as sometimes the MPPT is the source and sometimes the batteries are the source. If you have a separate set of wires directly from the battery to load then you can have a CB between MPPT and batteries but then you need a CB/battery disconnect on the load cables depending on the maximum possible draw. I think you have a Victron MPPT. Some Victron MPPTs have terminals for load and others do not.

I would be inclined to have a DC CB between PV and MPPT and a battery disconnect between batteries and load. A second DC CB would be superfluous between MPPT and batteries. Just make sure your cables are specced properly. 

You are correct, it's Blue. There is also no Load option for this MPPT, only PV and Battery so direction is always one-way. Thanks for your input.

OK CB on PV to MPPT and depending on load CB/battery disconnect  between battery and load I have seen a 125A DC CB but they are not common.

 

Edited November 27, 20205 yr by Chris Hobson

Thanks. The load current will not be nearly as much, it will be in the 20'ish range. The rest of the system is all sorted good and well, just needed to get that MCB polarity thing clear in my head.

I found this useful document that describes the correct wiring of DC Circuit Breakers in PV applications.  

Discussion-Paper-Correct-Wiring-of-Double-Pole-DC-Breakers-LVL2-131210-v2.pdf

1 hour ago, NigelL said:

I found this useful document that describes the correct wiring of DC Circuit Breakers in PV applications.  

Discussion-Paper-Correct-Wiring-of-Double-Pole-DC-Breakers-LVL2-131210-v2.pdf 1.67 MB · 2 downloads

Thanks @NigelL, it's exactly as Chris explained and I have it now - great reference document. It won't go up in flames this side...

On 2020/11/27 at 10:40 AM, Ingo said:

The rest of the system is all sorted good and well, just needed to get that MCB polarity thing clear in my head.

I just want to check you have a combiner box for your 5S/2P array.

12 minutes ago, Chris Hobson said:

I just want to check you have a combiner box for your 5S/2P array.

I do, Yes.

😅 ressurecting old thread! haha

@Chris Hobson & @Ingo Look at this. NoArk breakers on Andy's Garage, Awesome channel. O yeah, @NigelL THANK YOU for that doc.

Look at how he is connected switching off/on doing temp test in 40deg weather, nothing blowing up.