Combiner box question

[Mooreja]

Would a small combiner box double my amps if I attached two strings of solar panels in series?
Would the combiner box act like a series/parallel conbection?

 

[wattmatters]

A combiner box is just a convenient way to connect individual strings in parallel for a combined output. The current and voltage arising from such a panel arrangement is independent of the combiner box and is a function of the array arrangement and downstream load factors.

If your question was whether adding a second equally sized string of panels in parallel with the first string result in current doubling? Then the answer is yes, provided there is no restriction on the load and both strings are exposed to the same level of irradiance.

 

[rmaddy]

FYI - you do not need a combiner box if you only have two strings in parallel. Joining the two strings with MC4 Y-connectors is all you need.

A combiner box is typically only used with 3 or more parallel strings. It does act as the parallel connection. It does not act at all like a series connection. Simply connect two or more panels + to - for a series connection.

 

[Mooreja]

FYI - you do not need a combiner box if you only have two strings in parallel. Joining the two strings with MC4 Y-connectors is all you need.

A combiner box is typically only used with 3 or more parallel strings. It does act as the parallel connection. It does not act at all like a series connection. Simply connect two or panels + to - for a series connection.

I've got six 235w panels (37voc). I've got 3 strings, 2 panels in series, so putting each string in a combiner box does increase the amps? I want to expand on this in the future by adding a panel or two to each string in the future.

 

[Mooreja]

A combiner box is just a convenient way to connect individual strings in parallel for a combined output. The current and voltage arising from such a panel arrangement is independent of the combiner box and is a function of the array arrangement and downstream load factors.

If your question was whether adding a second equally sized string of panels in parallel with the first string result in current doubling? Then the answer is yes, provided there is no restriction on the load and both strings are exposed to the same level of irradiance.

I've got six 235w panels (37voc). I've got 3 strings, 2 panels in series, so putting each string in a combiner box does increase the amps? I want to expand on this in the future by adding a panel or two to each string in the future

 

[rmaddy]

I've got six 235w panels (37voc). I've got 3 strings, 2 panels in series, so putting each string in a combiner box does increase the amps? I want to expand on this in the future by adding a panel or two to each string in the future.

With things in parallel you add the amps. With things in series you add the voltage. When you have things in both you add both.

So with 6 panels in 2S3P you have 2 times the voltage and 3 times the amperage of a single panel.

If you add a panel to each string so you have 9 panels in 3S3P then you will have 3 times the voltage and 3 times the amperage.

 

[wattmatters]

I've got six 235w panels (37voc). I've got 3 strings, 2 panels in series, so putting each string in a combiner box does increase the amps? I want to expand on this in the future by adding a panel or two to each string in the future

Yes, this will increase the amps of the output from the combiner box. The voltage will be 2 x single panel voltage, while the current will be 3 x the single panel current.

It's the same arrangement I have.

3 parallel strings of 2 panels each. My panels are 370W each (Voc 40.9V, Isc 11.52A). This arrangement suits the solar input of my inverter as it has a 105V Voc limit. But you need to ensure the cable from the combiner box to the solar controller is of a sufficient gauge to carry the higher current.

 

[Mooreja]

Yes, this will increase the amps of the output from the combiner box. The voltage will be 2 x single panel voltage, while the current will be 3 x the single panel current.

It's the same arrangement I have.

3 parallel strings of 2 panels each. My panels are 370W each (Voc 40.9V, Isc 11.52A). This arrangement suits the solar input of my inverter as it has a 105V Voc limit. But you need to ensure the cable from the combiner box to the solar controller is of a sufficient gauge to carry the higher current.

View attachment 73253

Thank you. That answers my question.

 

[Mooreja]

With things in parallel you add the amps. With things in series you add the voltage. When you have things in both you add both.

So with 6 panels in 2S3P you have 2 times the voltage and 3 times the amperage of a single panel.

If you add a panel to each string so you have 9 panels in 3S3P then you will have 3 times the voltage and 3 times the amperage.

Thank you. This really helps.

 

[Bossrox]

A combiner box just joins together several strings of panels & the more strings, the more current you'll get. Amps always stay the same in series no matter if it's a few panels or a dozen, it's the voltage that increases when wired in series.

 

[MrBadger]

A combiner box just joins together several strings of panels & the more strings, the more current you'll get. Amps always stay the same in series no matter if it's a few panels or a dozen, it's the voltage that increases when wired in series.

but that does not answer what combiner box affects coming out of the combiner box. maybe super dumb question, but getting tired...
i understand going in...series parallel.
so far max voc is 145V and either max 50A or max pv charging current 0-80A. i dont know which one to use...
i've got 48V system. panels are 44.5V each and 9A.
so far... i could have 2P4S at 89V and 36A. going into combiner box a 40 amp breaker..
what can i add? just 1 more single panel to a 15A breaker? then do what for addition going out of box? can't find internet answers combiner box adds or doesn't add Volts amps... i know dumb question...but stuck

 

[wattmatters]

i could have 2P4S at 89V and 36A. going into combiner box a 40 amp breaker..
what can i add?

All strings in parallel need to be of the same voltage, which effectively means the same number of the same spec panels.

So assuming your change controller can accept the extra capacity (keeping in mind any Voc or Isc limits) you can either
- add extra panels to each string, or
- add an extra string with the same number of the same panels in parallel with the other strings.

Let's say you wanted to increase the capacity of your 8 panel 2P4S array by 50%, make it a 12 panel array.

You could go with 2P6S or 3P4S.

2P6S would mean voltage of the array increases by 50% while combined current does not change. In general you won't need a combiner box to do this.

3P4S would mean voltage stays the same while combined current increases by 50%. This is when you'll be advised to use a combiner box.

Which is preferable depends on a few things such as the physical array arrangements (e.g. are individual string facing different orientations), shading profile and charge controller specifications (MPPT operating range).

By the way, that array of mine I mentioned earlier which was in a 2S3P arrangement, I recently changed charge controller from one with a Voc limit of 105 V to one with a Voc limit of 500 V, so I changed the array configuration from 2S3P to 6S1P. 1/3rd the current but three times the voltage.

 

[MrBadger]

All strings in parallel need to be of the same voltage, which effectively means the same number of the same spec panels.

So assuming your change controller can accept the extra capacity (keeping in mind any Voc or Isc limits) you can either
- add extra panels to each string, or
- add an extra string with the same number of the same panels in parallel with the other strings.

Let's say you wanted to increase the capacity of your 8 panel 2P4S array by 50%, make it a 12 panel array.

You could go with 2P6S or 3P4S.

2P6S would mean voltage of the array increases by 50% while combined current does not change. In general you won't need a combiner box to do this.

3P4S would mean voltage stays the same while combined current increases by 50%. This is when you'll be advised to use a combiner box.

Which is preferable depends on a few things such as the physical array arrangements (e.g. are individual string facing different orientations), shading profile and charge controller specifications (MPPT operating range).

By the way, that array of mine I mentioned earlier which was in a 2S3P arrangement, I recently changed charge controller from one with a Voc limit of 105 V to one with a Voc limit of 500 V, so I changed the array configuration from 2S3P to 6S1P. 1/3rd the current but three times the voltage.

I'll simplify my question to verify i got this correct.
My combiner box has up to 3 spots for breakers. I use Mp4 fuse connectors outside before the box.
If I use 2 or three breakers.....my question is......the pos and neg wire LEAVING the combiner box (DCvoltage out) going to the charge controller....the voltage is the same as each breaker.... ?
YOur first line above....all strings in parallel need to be same voltage...does that mean the obvious of each panel's voltage? of course i'm only using one type of panel always. not mix matching dif types of panels... OR...
do you mean each parallel group going onto a breaker must be the same voltage? because the breakers are all on a piece of metal, thus combining all the breakers in a way..before exiting the combiner box.... so...maybe you mean each of my breakers MUST have the same sum amount of voltage onto that breaker...? for example,,,
I can't have
- one 30 amp breaker hooked up to 9 panels (3P3S=9+9+9Amps and just 133.5 volts because each series is 44.5x3 and combined via Y connector branch connector... AND
-a different breaker beside it that is connected to just 1 panel being 44.5V and 9A. you mean I can't have different voltages connected in the breaker panel box. that would be silly right? like mix matching a typical house breaker panel... its always just 120v one leg and or 2 legs of 120V. but combiner boxes have only one hot leg being the positive out..so i'm guessing yeah...of course each breaker must be same voltage.

poor charge controllers some how have to fix these weird voltages to go back to whatever the battery its charging needs...magically.

so if i get this correctly.....I could do 3P3S twice. one on each 30 amp breaker. same same voltage each breaker. total still just adds the amps inside the breaker combiner box to 54Amps which is between 0-80A pv charging current parameter listed for my SRNE charge controller.
Or I'm wrong and haven't got a clue what the parameter means that says "MAX PV current=50amps" still can't get an answer about that tech spec.

 

[wattmatters]

I'll simplify my question to verify i got this correct.

I thought you were going to simplify the question.

Sorry but you post is too much of a ramble. If you do not know how to correctly wire up a PV array to a charge controller/inverter then my advice is don't. Either get someone in who does know what they are doing, or do some reading on how to correctly wire solar PV systems.

There are a range of resources in the forum you can read:

Resources

diysolarforum.com

This one in particular might help:

Fusing & Wire Sizing guidelines for solar panels

To get the paper, click on the orange'' button at the top of the screen. This resource is intended to help the user understand when they need to add Over Current Protection Devices (OCPDs - Fuses or Breakers) to the solar panel array and what...

diysolarforum.com

 

[740GLE]

Maybe a separate thread is in order.

 

[Bossrox]

but that does not answer what combiner box affects coming out of the combiner box. maybe super dumb question, but getting tired...
i understand going in...series parallel.
so far max voc is 145V and either max 50A or max pv charging current 0-80A. i dont know which one to use...
i've got 48V system. panels are 44.5V each and 9A.
so far... i could have 2P4S at 89V and 36A. going into combiner box a 40 amp breaker..
what can i add? just 1 more single panel to a 15A breaker? then do what for addition going out of box? can't find internet answers combiner box adds or doesn't add Volts amps... i know dumb question...but stuck

I can't make out what you're trying to accomplish. Personally I don't use or like combiner boxes adding many strings together at the panels just requires using heavier wire for a run to the charger. I bring each string right to the charger then use a ground buss bar to combine all the strings so I get a just a short pigtail sized to the total amps it needs to carry.