Circuit breakers and midnite combiner box mnpv6

[Pyana1]

i have 4 panels [I'd like to add one more using a combiner box] tied in parallel using 3 sets of mc4y connectors. My (isc per panel is 8.57) so i am assuming the correct mathematics when it comes down to choosing the proper circuit breaker in my case would be 4 * 8.57 = 34.28 * 125% = 42.85 rounded 45.00 amps .

and for my newly added panel with the same isc, I'd simply multiple 8.57 * 125% = 10.71 rounded to a 12 amp circuit breaker .

Are my four panels currently tied in parallel considered a string and if so, do I leave it like that and just purchase a 45 amp circuit breaker? and why is that I can only find 2 pole 45 amp breakers, looks like it's twice the size of a regular circuit breaker.

[Sunking]

Why? You would most likely just be throwing money away.

Use a MPPT controller, wire all the panels in series, use mucch smaller wire, and no need for fuses and combiner. You don't need a combiner until you have 3 parallel string or more than 8 panels.

[Pyana1]

Why? You would most likely just be throwing money away.

Use a MPPT controller, wire all the panels in series, use mucch smaller wire, and no need for fuses and combiner. You don't need a combiner until you have 3 parallel string or more than 8 panels.

Ok great... I currently have a 60 amp morningstar mppt controller , I though about using another set of mc4y connectors to add the last (5th) panel but thought the combiner would help make things smoother !

[paulcheung]

What is the VOC on these panels? 4 in a series may be too much voltage in a cold country.

[Pyana1]

What is the VOC on these panels? 4 in a series may be too much voltage in a cold country.

Here are the specs, they're attached to HIS picture. i have everything set up in Haiti where it's usually 90-100 f

[paulcheung]

At 37.87 VOC it is too much for 4 in series with the Morning star CC. you have to wire the panels with 2 in series and 2 string parallel.

[Naptown]

5 panels are tough to do
Too much voltage for a single string and cannot be split into 2 even strings
About the only choice you have without adding another charge controller is to wire in parallel.
Then each panel will require a fuse at the combiner.
If say you added 2 more panels then you could wire in 2 series strings and use smaller wire and no fuses or combiner. That is if your existing charge controller can handle the amps.
What battery voltage are you running.

[Pyana1]

5 panels are tough to do
Too much voltage for a single string and cannot be split into 2 even strings
About the only choice you have without adding another charge controller is to wire in parallel.
Then each panel will require a fuse at the combiner.
If say you added 2 more panels then you could wire in 2 series strings and use smaller wire and no fuses or combiner. That is if your existing charge controller can handle the amps.
What battery voltage are you running.

12 volts, my CC isc is 48 amps, adding this addition panel will have me somewhere around 44 amps .

so I have 4 panels in parallel, does the Isc remain the same?

[Sunking]

so I have 4 panels in parallel, does the Isc remain the same?

You could not get 48 amps with 6 of those panels in parallel. Your total panel current is going to be around 16 to 17 amps in 2 x 2



5 is a Prime Number and only leaves you two possible configurations of all in Parallel or all in Series. Unfortunately Series is out of the question because it exceeds the Controllers input voltage. Highest you can go in series is 3 to 4 panels. That leaves you with all in Parallel which is the LAST THING YOU WANT TO DO

With 4 panels, if possible, and if the numbers work, you want them all 4 in Series. However in your case will not work with all 4 in series because it exceeds the CC maximum Input Voltage. You want them 2 x 2, or 2 in series, in parallel with, 2 more in series. That will give you roughly 15 amps current into the Controller. No Fuses or combiners needed.

Forget NEC Calculations on the wire between panels and CC, they will likely be way too small if any distance is incurred. NEC will come up with 12 AWG, maybe 10 AWG. Perfectly safe and if the one-way distance between panels and controller are 10 feet or less would work. But once you get over 10 feet and you start running some serious wire power losses exceeding 2%. To keep losses to 2% or less requires over sized wire. By wiring panels in series operating at higher voltages helps avoid some of the cost. But Forget using NEC formulas initially. Use Voltage Drop Calculators, then check NEC calcs and use whichever is the largest wire. Only time it would be NEC is very short cable runs.

[Pyana1]

5 is a Prime Number and only leaves you two possible configurations of all in Parallel or all in Series. Unfortunately Series is out of the question because it exceeds the Controllers input voltage. Highest you can go in series is 3 to 4 panels. That leaves you with all in Parallel which is the LAST THING YOU WANT TO DO

With 4 panels, if possible, and the numbers work, you want them all 4 in Series. However in your case will not work all 4 in series because it exceeds the CC maximum Input Voltage. You want them 2 x 2 or 2 in series, in parallel with 2 more in series.

I'm new to RE so I hope you'll have a little lenience towards me, loll; nevertheless why would 5 panels in parallel be bad?.... I've got one load which is a Haire chest freezer 12 amp start up and 1.69 running that I just can't get my 60 amp CC to go into "absorption" mode with . I'm in Haiti but I've only got about 3 days to head back to Miami . And that's why I was thinking about adding a last panel so I can keep my SOC somewhat balanced

[foo1bar]

nevertheless why would 5 panels in parallel be bad?....

Need 5 fuses/breakers
Equipment it feeds into needs to be able to accept that low of a voltage with that high of current.
And the replacement for that equipment which you'll be buying in 15 years needs to as well.

Would 6 panels work out better?
You would have 4 options for how to wire them.
1x6
2x3
3x2
6x1

Most likely 6 in series would be too high voltage.
And 6 in parallel would be too low voltage / too high current.
But the other two options(2x3 or 3x2) might be better suited to your equipment than 5x1 or 1x5

[paulcheung]

Ok great... I currently have a 60 amp morningstar mppt controller , I though about using another set of mc4y connectors to add the last (5th) panel but thought the combiner would help make things smoother !

.

Some thing is wrong with your system. you don't need more panels. your Morningstar 60 amps controller actually too small for these 4 panels wired to 12 volts bank. these panels should give about 80 amps on 12 volt battery bank.

[Pyana1]

.

Some thing is wrong with your system. you don't need more panels. your Morningstar 60 amps controller actually too small for these 4 panels wired to 12 volts bank. these panels should give about 80 amps on 12 volt battery bank.

that is what I had initially thought, by HIS grace, but I was told due to heat losses etc, it's about 90 plus here daily, that i was loosing amps. Plus, although the sun rises around 6:30am-ish, I don't see decent light to roughly 8:40-9 due to tree shading that I'm currently try to resolve with the owner of the property.

Efficient is now my objective: I just switched the volts on my inverter from 120 to 115 I should have the kill a watt readings later tonight around 9.

What's your angle Paulcheung, what do you suggest i do?

[Pyana1]

12 volt battery bank, 450 amp hours, 1005.5 PV, 60 amp CC

[paulcheung]

I would wire them 2 in series and 2 string parallel to see the wires loss cause that much lost. I get 60 to 65% name plate in average, you should get 50 amps in average.