Parallel After a 4 in 2 out Combiner Box

[MrM1]

I have 2 of these Watts247 4 in 2 out Combiner boxes.

Because of endless trouble I've had with a Growatt SC48120 charge controller, it may be necessary to switch to another brand of SCC. I built the system around the idea of 2 arrays going to the 2 mppt trackers of the external Growatt SCC, and 2 arrays going to 2 mppt trackers of the Growatt 12k inverter.

But now I am looking at buying a Midnite Solar Barcelona solar charge controller that only has 2 mppt tracker inputs.

Question: would it be a bad idea to combine the 2 outputs of each combiner in parallel into a single output from each combiner after they leave the box? I would not exceed the 600v DC of the Barcelona nor would I be exceeding the wattage input.



Here are the breakers before each input goes into each mppt tracker of the chargers

 

[MisterSandals]

Question: would it be a bad idea to combine the 2 outputs of each combiner in parallel into a single output from each combiner after they leave the box? I would not exceed the 600v DC of the Barcelona nor would I be exceeding the wattage input.

What are the volts and amps of each array going into the combiner boxes?
What are the amp ratings of the fuses/breakers in the combiner boxes?
Are the combiner boxes themselves rated with max amps and volts?

There are probably several options to combine the arrays to work with a different SCC. Possibly with a combiner box(es) too.

 

[timselectric]

Question: would it be a bad idea to combine the 2 outputs of each combiner in parallel into a single output from each combiner after they leave the box? I would not exceed the 600v DC of the Barcelona nor would I be exceeding the wattage input.

Yes, that's fine.
Just size the wiring and OCP accordingly.

 

[MrM1]

What are the volts and amps of each array going into the combiner boxes?
What are the amp ratings of the fuses/breakers in the combiner boxes?
Are the combiner boxes themselves rated with max amps and volts?

There are probably several options to combine the arrays to work with a different SCC. Possibly with a combiner box(es) too.

Sorry. I knew better than to not provide that info.

360w bifocal panels x32
8 strings
VOC = 47.6 X 4 = 190.4 per array string
ISC = 10.06 Amps per panel

Have 8 arrays going into 2 combines. Each combiner is a 4 in 2 out. I Can't recall the fuse and Breakers in the combiner boxes. But the are rated for 2 x 64 Amp max output

I have #10 solar wire from each 4 panel array to the combiners and then #8/2 SOOW x 4 from the combiners to the SCCs.

My 4 disconnect Breakers for each pair of combined arrays inside the trailer are 40 Amps x 4 Breakers.

So it would be OK to connect both #8 soow cables together to go into a single mppt tracker in the Barcelona ( one pair from combined box 1 and 1 pair from combiner box 2) into the 2 mppt trackers of the Barcelona?

I'm not concerned about the Barcelona input voltage. It's 600v. It can charge at 200 Amps total which is a little low. My array is capable of about 225 + Amps, but I know Midnite gear can handle being over paneled.

But should I use a busbar or put 2 wires under 1 lug in the Barcelona?

 

[Prince Of Darkness]

Hi MrM1,

Seens that with a string Voc of about 190.4 V, that you might be too low for the stated operating input voltare of the Barcelona:

"Operating Voltage of 185 to 585 volts"

Guess that you have 32 PVs, now and so on ...

Just sayin', you might check with Ryan, on the MidNite Forum (IIRC, you are a member there).

FWIW, Luke

 

[MrM1]

Hi MrM1,

Seens that with a string Voc of about 190.4 V, that you might be too low for the stated operating input voltare of the Barcelona:

"Operating Voltage of 185 to 585 volts"

Guess that you have 32 PVs, now and so on ...

Just sayin', you might check with Ryan, on the MidNite Forum (IIRC, you are a member there).

FWIW, Luke

Could I connect my 2 outputs out of each combiner in series. That'd give me near 400v DC

 

[WindWizard]

I would use just one of the two combiner boxes and run your panels 8S x 4P. This would put your voltage at 380 Volts at 20 amps for each leg coming out of the combiner box. Then you do not have to double up the wires on the Barcelona.

Another way to do this would be to connect a wire from one of the positive connectors to the negative on each of the combiner boxes and then run the remaining positive and negative into the barcelona. This would double the voltage coming out of each combiner box, so that rather than two outputs out of each combiner box, there would only be one.

 

[MrM1]

New thought. I could buy 4 Midnite Classic 250 SLs for about the same price price as a Barcelona and breaker panel (for the Barcelona) and leave the wiring as is.

So many decisions. ?

 

[WindWizard]

Or parallel the outputs of each combiner box and buy two Victron 250/100 Charge Controllers. You will never regret buying these. I replaced my Outback FM-80's with the Victron's and the performance has been outstanding.

 

[MrM1]

Or parallel the outputs of each combiner box and buy two Victron 250/100 Charge Controllers. You will never regret buying these. I replaced my Outback FM-80's with the Victron's and the performance has been outstanding.

That is indeed in the consideration too. Thanks. That is probably the most cost effect way to go

 

[MrM1]

What we decided ...

I'm first going to try a Sigineer scc because it has the same form factor, connections, 2 mppt trackers and DC Input spec as the Growatt sc48120.

But I'm not optimistic as the Sigineer seems to be cut from the same cloth as the Growatt. They're identical looking with some different form factors in the Case. My hope is sigineer tweaked and improved the firmware. I can't get any confirmation about that.

Problem I'm (currently) having with the Growatt, is that if my DIY 280ah 48v x2 battery's BMSs disconnect from the charing due to low temp cut off the Growatt scc doesn't know what to do and throws the Growatt 12kw inverter into a code 03 DC over voltage fault at 63+v DC. Oddly, the built in scc of the Growatt Inverter does not NOT do this, just the external scc.

But if the Sigineer does not work, we're buying a single Victron and will parallel the 2 combiner box outputs into the one Victron scc .

 

[OzSolar]

New thought. I could buy 4 Midnite Classic 250 SLs for about the same price price as a Barcelona and breaker panel (for the Barcelona) and leave the wiring as is.

So many decisions. ?

Have you bumped into the Victron 450/100 yet? Two MPPT's.

 

[WindWizard]

What I have found after the two Outback FM80 CC's that I had were overpowered so I needed to replace them, was that the two Victrons 250/100 that I purchased seem to be putting out a lot more power. It is still the winter months, so the jury is still out, but on Feb 1st I had a 41kwatt day of Solar production. Last year the best I did was 32kw.

Sometimes the Solar charge controllers are producing the full 100 amps each which is 20 more amps over what the Outbacks were capable of. The other thing about the Victrons that I notice is that they have no annoying fan that runs most the time. They also seem to be very responsive to the changing sun conditions. If I was to rate the Victron Charge Controllers, they would get an A vs a B for the Outback. I managed to snag the two of them for $1200 on Ebay. My wife decided that we were not going to go cheap on the Solar System. Buy quality products and then you do not have to pay twice or thrice for them.

We put the System together to supplement our power bill. My wife did not want anything to do with Grid Tie, so from day 1 it was an Off Grid setup. Like a lot of you we started small and then expanded. We are up to 30 panels now. The System is fully automated, and it basically does what you would want it to. It supplies the whole house when the LFP's have enough Solar in them and then when the Cells get low it Automatically switches back to CMP which is now up to 26 cents per kw. Last year it saved us $1900 on electric bills.

The whole point that I wanted to make is that it is my recommendation to not go cheap on the Charge Controllers because if they do not produce as well as the more expensive ones, then you will not only lose power, but you will probably have to buy them again in a few years.

 

[MrM1]

Have you bumped into the Victron 450/100 yet? Two MPPT's.

Yeah it's really too much and costs go up too. I could probably do 1 vic 250/100 and b good

 

[OzSolar]

Yeah it's really too much and costs go up too. I could probably do 1 vic 250/100 and b good

I just wanted to throw it out there.

What am I missing? You said you have 36 modules at 360w each. That looks 11.52 kW to me which doesn't seem to line up with one Victron 250/100 very well at all.

Of course each case is different but the 450/100 was the best solution for me since I had two strings of with different number of modules and different shading issues so I had to have more than one MPPT or SCC. Plus my modules have a Voc of 50v so I was really hamstrung there. So much more flexibility with the 450 Voc.

 

[MrM1]

My bad. The scc I'd be replacing only uses half (16) of the modules. The other half is connected to the Growatt 12kw AIO which works perfectly fine . If not the 450/100 would be ideal . Or the Midnite Solar Barcelona.