Charge Controller / Panels Question(s)

[kelsol]

System: 6x12v 130AH FLA batteries, parallel.
4/0 x 6 1ft cables
1 400A ANL fuse (to inverter)
6 x 100W 5-18v Monocrystalline PV panels
1 60A MPPT makeskyblue MPPT controller
1 4Kw(8kwPeak) Sine Wave inverter.

I have pretty much covered all the info and material I (believe I) need, and now working from battery bank up.

I have a MakeSkyBlue 60A MPPT controller. As yet untested.

Instructions recommend using 2 9AWG for each terminal (4 for 2 pos/negs) on input and output (8 wires w/o the additional 5A DC out connection).
It also recommends 100A double throw breakers for input and output.

First issue: I cannot seem to source 9awg in copper. 8awg can fit, but tight. Ordered 50 ft of it at least for initial testing. Are there any issues with using this gauge wire if I can.

Second issue: Since 2 wires are used in place of 1 - I am thinking of using 3-1 MC2 connectors and using 2 sets of 3 panels in parallel, and use the resultant 2 positive wires to the controller as the 2 poles of a 50A DPDT type (dual pole) breaker. I was wondering if I can use the breaker as a switch. In reality I would only be using this setup as emergency backup, so wear woud be minimal by manual switching of breaker.

Third issue: Can I do the same from controller to batteries?

Can anyone recommend a good source/brand of these type of breakers at a hopefully reasonable price. If switches are needed can knife switches be used?

I would like to be able to wire (8AWG) with lugs the breakers, instead if using a panel/busbar setup type. As mentioned at least for now I want the system to be very basic but reasonably safe. I may have need for 12v at high capacity for other applications, hence the 12v parallel setup, and heaviest AWG I can handle.

 

[sunshine_eggo]

I have a MakeSkyBlue 60A MPPT controller. As yet untested.

Instructions recommend using 2 9AWG for each terminal (4 for 2 pos/negs) on input and output (8 wires w/o the additional 5A DC out connection).
It also recommends 100A double throw breakers for input and output.

From PV to MPPT? That's insane, especially with only 600W. In most installations, a single set of 10awg will suffice.

First issue: I cannot seem to source 9awg in copper. 8awg can fit, but tight. Ordered 50 ft of it at least for initial testing. Are there any issues with using this gauge wire if I can.

No harm in using thicker wire, except to our wallet.

Second issue: Since 2 wires are used in place of 1 - I am thinking of using 3-1 MC2 connectors and using 2 sets of 3 panels in parallel, and use the resultant 2 positive wires to the controller as the 2 poles of a 50A DPDT type (dual pole) breaker. I was wondering if I can use the breaker as a switch. In reality I would only be using this setup as emergency backup, so wear woud be minimal by manual switching of breaker.

Mind boggled. No clue why they would specify a 100A breaker. The need for breakers and their size depends on the panels and their configuration.

Third issue: Can I do the same from controller to batteries?

600W/12V = 50A or size for the 60A max output.

 

[rmaddy]

All of your questions seem to be related to wiring up the panels and the solar charge controller (SCC). Let's look at each half of that.

How far is it from the SCC to your batteries? The wires from the SCC to the batteries need to support the 60A max output of the SCC. If the wires from the SCC to the batteries are about 5' long or less then you should be using 6AWG wire. There should also be a 75A fuse between the SCC and the batteries.

How far is it from the panels to the SCC? You only need one pair of wires from the panels to the SCC. All of the panels should be joined together near the panels and then the one final pair after all of the connections runs to the SCC. The SCC has a Voc range of 20V - 80V on a 12V system. Depending on the exact specs of your panels you probably will need a 2S3P panel arrangement. 3S2P would be easier but the Voc might be too high. Get a pair of 3-to-1 MC4 connectors to connect the panels in 2S3P. Use 3 MC4 inline fuses for each of the 3 parallel strings. A pair of 10AWG wires is probably plenty from the connectors to the SCC if the length isn't too long.

You will want a PV disconnect breaker close to the SCC. This should be a 2-pole DC breaker rated for at least 100V and about 30A or more. It will only be there as a disconnect, not to protect anything. Just make sure the amperage is higher than what your panel arrangement can put out.

I have no idea why MakeBlueSky suggests using 2 pairs of wires and 100A fuses. Makes no sense.

 

[kelsol]

From PV to MPPT? That's insane, especially with only 600W. In most installations, a single set of 10awg will suffice.
No harm in using thicker wire, except to our wallet.
Mind boggled. No clue why they would specify a 100A breaker. The need for breakers and their size depends on the panels and their configuration.
600W/12V = 50A or size for the 60A max output.

While 60A might be a theoretical max, I believe the electical recommendation is 1.25 Imax, for 75A, w/ 100A probably being acceptable. With potential high inductive loads (freezers, motors), 100A doesnt seem all that unreasonable - but I might be wrong!

The use of dual posts for each connection appears to allow for smaller (higher AWG) wiring in parallel for larger currents. 2 x 8AWG vs 1 6AWG. Keeping in mind that this is being designed as a semi-modular 12V system.

Of interest is that the 4Kw inverter came with 2x 2/0 cables instead of 1 4/0 cable per polarity.

My issue of concern at this point is the basics of the double breaker itself. My idea is to have 3 panels per positive 8AWG wire (after MC4s) going into each side of the dual breaker. Assuming 50A on each side, should the dual breakers be rated at 50A , or 100A? Cumulative or max branch?

I would be looking for appropriate breakers that can directly handle 8AWG instead of 'panel' type connectors.

Here the primary concern is PVs -> SCC

 

[kelsol]

Duplicate

 

[kelsol]

How far is it from the SCC to your batteries? The wires from the SCC to the batteries need to support the 60A max output of the SCC. If the wires from the SCC to the batteries are about 5' long or less then you should be using 6AWG wire. There should also be a 75A fuse between the SCC and the batteries.

I will want to keep the SCC - Batteries distance short: A few feet, on perhaps a small wood or plastic support panel, with maybe an additional CPU type fan for cooling.
6AWG will not fit in the SCC , which is apparently designed to accept 8AWGx2 per connection. (Though 'instructions' recommend 9AWG!)

How far is it from the panels to the SCC? You only need one pair of wires from the panels to the SCC. All of the panels should be joined together near the panels and then the one final pair after all of the connections runs to the SCC. The SCC has a Voc range of 20V - 80V on a 12V system. Depending on the exact specs of

The panels, so far in planning, would have a cable length of 30 ft. They are all identical in model and brand. I would like to keep them all in parallel as to allow an easy modularization. Like pulling a panel temporarily, hooking it to a cheap PWM to charge a battery, or run a fan - while allowing the rest of the system to run also. I might also want to 'borrow' 2 panels to run another cheap PWM to charge a UPS at 24v.

I imagine 2 pairs of 3->1 MC4s going to a double switch/breaker (75-100A?)
Am I going to need separate fusing for the 3->1 MC4 lines or will the switch/breaker do? Are there such line cables with fuses preinsstalled? I can always add a fuse if necessary, as I know how to wield a soldering gun.

Maddy
your panels you probably will need a 2S3P panel arrangement. 3S2P would be easier but the Voc might be too high. Get a pair of 3-to-1 MC4 connectors to connect the panels in 2S3P. Use 3 MC4 inline fuses for each of the 3 parallel strings. A pair of 10AWG wires is probably plenty from the connectors to the SCC if the length isn't too long.
/Maddy

Is 30Ft too long? I might want to stick with 8AWG .
Iss there a good source of the MC4 cable with inline fuses. The net seems overpriced, local electrical suppliers and Lowes dont handle DC. There are some marinas around here, but is there a Radio Shack for this type of stuff???

You will want a PV disconnect breaker close to the SCC. This should be a 2-pole DC breaker rated for at least 100V and about 30A or more. It will only be there as a disconnect, not to protect anything. Just make sure the amperage is higher than what your panel arrangement can put out.

I have no idea why MakeBlueSky suggests using 2 pairs of wires and 100A fuses. Makes no sense.

Higher current capacity. It appears the lower priced 'true' MPPs top out at around 60A, and have dual connecters of lower capacity in parallel (2x8AWG vs 1x6AWG) - perhaps for cost considerations.

It 'recommends' 100A dual breakers but am not certain if 50A is whats realistic in a dual configuration!

Apologies for any duplicate replies - mouse seems to be bouncy today..

 

[rmaddy]

6AWG will not fit in the SCC , which is apparently designed to accept 8AWGx2 per connection.

Very strange that a 60A controller isn't built to accept the proper sized wire. Forcing you to use pairs of smaller wires is a bad design and more difficult to fuse.

I would like to keep them all in parallel as to allow an easy modularization

With the panels in 6P you can ignore most of what I said earlier about the wiring for the panels. Post the full specs of your panels so proper advice can be given to handle this arrangement.

It 'recommends' 100A dual breakers but am not certain if 50A is whats realistic in a dual configuration!

You definitely do NOT want a 100A breaker on 8AWG wire. 8AWG can burst into flames before it gets to 100A.

 

[kelsol]

These are Weize 100W monocrystalline

Maximum Power Output: 100W
Maximum Power Voltage (Vmp): 18.78V
Maximum Power Current (Imp): 5.32A
Maximum System Voltage: 1000V DC
Open-Circuit Voltage (Voc): 22.64V
Short-Circuit Current (Isc): 5.7A

I am looking at 3p *2 for going to the SCC.
Question is where to source the proper fusing?
3 10A per positive line, or could I get by with 1 30A per line?