@jason compo you will not like what I am going to say now.

In todays world, we should all become more independent and have a big drum of salt to be used for so called professional advice and opinions.  For instance, I don't trust 99% of doctors anymore.  The reasons are obvious - to some.

However, there is a minimum of understanding that is ABSOLUTELY required to do any job.  If you want to paint, you must at least know that you use water and not thinners to dilute your PVA paint, or clean the PVA paint brush.

With regards to your panels, we are dealing with very simple, elementary circuits.  High school science.  We are talking about wiring and configuring a rather expensive system that involves DC voltages of 250V and maybe more, if you connect it wrong.  250VDC is more dangerous than 220VAC.  If you, at this stage, still get confused, then I would SERIOUSLY RECOMMEND THAT YOU DO NOT ATTEMPT DOING THIS WORK YOURSELF.  Rather get a knowledgeable person to configure and wire your system.

27 minutes ago, jason compo said:

PLEASE READ THE FULL TOPIC.AS

Why is everyone giving me different answer to my question 

This is becoming very very confusing.PLEASE STOP

I would ask if you are not 100% sure on that is going on please do not commit  as I do not want to destroy my system 

Thank you 

I just read your other thread, to be honest your questions are the confusing part. If your system is already installed and working fine for one year dont change anything . You will most likely not increase your production by wiring it differently especially if you dont properly know what you are doing .

1 hour ago, jason compo said:

PLEASE READ THE FULL TOPIC.AS

Why is everyone giving me different answer to my question 

This is becoming very very confusing.PLEASE STOP

I would ask if you are not 100% sure on that is going on please do not commit  as I do not want to destroy my system 

Thank you 

I would ask if you are not 100% sure on that is going on please do not commit  as I do not want to destroy my system 

In my humble opinion with that kind of above request, you will not get much help in future. Diplomacy is the name of the game in this forum.

 

5 minutes ago, Antonio de Sa said:

I would ask if you are not 100% sure on that is going on please do not commit  as I do not want to destroy my system 

In my humble opinion with that kind of above request, you will not get much help in future. Diplomacy is the name of the game in this forum.

 

I have been from the beginning and in all of my post been polite in asking persons for knowledge on my solar system

In my humble opinion giving out wrong or incorrect information because persons have not read or misunderstood the topic from the beginning  only confuses people and  to the point where they can destroy they system does not help that person or the forum in any way. 

Giving out incorrect information could cost a person thousands off pounds which I am sure most people in this forum including me, can not afford so me asking people to fully read the topic is not wrong 

If you asked a question and you connected up your system in the wrong way and you destroyed your inverter would you be help. I think not

If you feel I am wrong because I am asking politely for the correct information and ask persons to fully read the topic then I wonder who is wrong

. If people do not what to respond to a post, that is there right of any person on this forum. 

Connecting up a powerful system wrong could in the worst case kill someone  whether person agree or disagree that is they right.

19 hours ago, jason compo said:

Hi all 

I have 6 x solar panels of 450w each 4 in series amd 2 in parallel as shown in the diagram.

How do I calculate the fuse size I need . please

Jason, reading through all the posts, I honestly think the people are trying to help you, BUT.....

nobody can give correct advice looking at your 2 drawings.

Both show 6 panels in series, not 4 series and 2 parallel.

Please supply us with the correct wiring diagram as it is installed at the moment.

Edit: And the Brand and specs of your PV panels

 

Edited April 15, 20233 yr by Virwat
Add Brand & specs of Panels

I only did one drawing which was trying to copy a drawing some one had posted because I did not understand the drawing they sent.

I am going to leave the panels as they right ,with the 3 strings

Thank you everyone that has tried to help

10 hours ago, jason compo said:

PLEASE READ THE FULL TOPIC.AS

Why is everyone giving me different answer to my question 

Because when you make statements like I have 4 in parallel with 2 more but you actually draw 6 in series then we have to guess. 

Different answers are given my different people. This is a forum not a school class where we repeat what the teacher just said. 

Edited April 15, 20233 yr by Scorp007

12 hours ago, jason compo said:

Would it be best to place 6 x panels IN PARALLEL on each MPPT ?

What inverter do you have, and what is the maximum panels you hope to invest in?

I would like to apologise to everyone that has tried to help. I made a mistake.

I started off a post on Solar setup and for some reason open up another on solar calculation .I have mixed the whole thing up thinking they where both attached and I have only realised my mistake now.

We all made mistakes unfortunately this was my one

Lets get back to the basics.
You have an inverter with 2 MPPTs each one with a max 4000W input. 
You have 12 solar panels at 450W, i.e. a theoretical 5400W. Whther in series or parallel, this total exceeds your max MPPT input by quite a bit and you are only using one MPPT from what we are able to establish.  This is not the most efficient way. Yes, the Inverter will probably clip excess Amps if they exceed the MPPT limit.
Ideally you would want to connect 6 panels each in series into each MPPT. 
I have no idea what that combiner box of yours does when you have 3 strings, each one with huge differential voltages. I can only imagine losses.
2 panels at ~100V VOC
4 panels at ~ 200V VOC
6 panels at ~ 300V VOC
Thus again, that 6 panel string should go to a set of 20A fuses then via a double pole DC breaker to the one MPPT.
The 2 and 4 panels strings should be strung as another 6 panels series string with it's set of 20A fuses via it's double pole DC breaker to the other MPPT.
That will give you a balanced solar input on both MPPTs and will be the optimised setup for the panels you have curtently.

 

 

5 minutes ago, zsde said:

Lets get back to the basics.
You have an inverter with 2 MPPTs each one with a max 4000W input. 
You have 12 solar panels at 450W, i.e. a theoretical 5400W. Whther in series or parallel, this total exceeds your max MPPT input by quite a bit and you are only using one MPPT from what we are able to establish.  This is not the most efficient way. Yes, the Inverter will probably clip excess Amps if they exceed the MPPT limit.
Ideally you would want to connect 6 panels each in series into each MPPT. 
I have no idea what that combiner box of yours does when you have 3 strings, each one with huge differential voltages. I can only imagine losses.
2 panels at ~100V VOC
4 panels at ~ 200V VOC
6 panels at ~ 300V VOC
Thus again, that 6 panel string should go to a set of 20A fuses then via a double pole DC breaker to the one MPPT.
The 2 and 4 panels strings should be strung as another 6 panels series string with it's set of 20A fuses via it's double pole DC breaker to the other MPPT.
That will give you a balanced solar input on both MPPTs and will be the optimised setup for the panels you have curtently.

 

 

I will need to buy  as few parts before I connect to the second MPPT as I do not want to go direct from the solar panels to the inverter.

I will need to buy a box to hold the DC breaker and the SPD  on Monday

Any suggestions on qhich one to get

Iwould  it best to disconnect 6 panels until I have if fixed correctly  ?

Continue to run your system until you have the needed parts.
A 20A or 32A DC breaker will do the trick.
What is the rating of the one DC breaker that you already have in your combiner box?

22 minutes ago, zsde said:

Continue to run your system until you have the needed parts.
A 20A or 32A DC breaker will do the trick.
What is the rating of the one DC breaker that you already have in your combiner box?

That combiner box only lacks a 2nd SPD that can be wired in the place of the 5th and 6th fuse as I indicated on the other thread. 

It seems that DC breaker is 63A.

The combiner is sold as a 6 string unit. 

https://www.ebay.com.au/itm/202638837275

3 minutes ago, Scorp007 said:

That combiner box only lacks a 2nd SPD that can be wired in the place of the 5th and 6th fuse as I indicated on the other thread. 

It seems that DC breaker is 63A.

The combiner is sold as a 6 string unit. 

https://www.ebay.com.au/itm/202638837275

I have a second SPD in-between the combiner box and the inverter as shown

Would this be a better combiner box to buy ?

54 minutes ago, zsde said:

The 2 and 4 panels strings should be strung as another 6 panels series string with it's set of 20A fuses via it's double pole DC breaker to the other MPPT.
That will give you a balanced solar input on both MPPTs and will be the optimised setup for the panels you have curtently.

@jason compoOnly thing I could add here, like I said on the other thread, is to consider the shade falling on your panels during the morning, and eliminate as many sources of shading as you can even if not all things are possible.

Once that is done, consider combining the shade-free panels on one string on one MPPT, and the shaded panels on the other string on the second MPPT.

Right now you are looking at a balanced 6+6 split which should be a major improvement and maybe that's already enough, but maybe a 8+4 split of shaded and unshaded could generate more power overall in your specific case, rather than to keep shaded panels dragging fown the performance of the sunny panels. For you to investigate and decide. 

 

Thank you for the information 

The panels are in this place until I have my house build 

Once that is done the panels will receive no shade due to the height and position of the house.

One question I only put the breaker would it be safe to connect a SPD aswell just in case ? 

2 hours ago, jason compo said:

Thank you for the information 

The panels are in this place until I have my house build 

Once that is done the panels will receive no shade due to the height and position of the house.

One question I only put the breaker would it be safe to connect a SPD aswell just in case ? 

If you go as suggested with 6 panels to each MPPT then you MUST use 2xSPD and cannot just use 1. The 2 strings will not be interlinked before going to the inverter. 

It is for this reason in my drawing I indicated that you just change the combiner before it was asked/said that you will just remove it or someone suggested do dump it. 

No problem using SPD and DC breaker outside of the combiner in another small DB. 

3 hours ago, jason compo said:

Would this be a better combiner box to buy ?

Indeed. That is the perfect combo for your set up at this time

 

So that I 100% understand I have drawn a diagram.

 

I am dyslexia so I find it easier with drawings 

Those 6 panels in series, then the fuses and the breaker with one SPD and then to MPPT 1.
The same again for the second 6 Panel series string and that then goes to MPPT 2.

Edited April 16, 20233 yr by zsde

At long last i finally understand the setup  of the system

Thank you so much for your time and patience with me

14 minutes ago, jason compo said:

At long last i finally understand the setup  of the system

Thank you so much for your time and patience with me

I was just about to say @zsde deserves an award for his patience.He has been the most helpful in both of your threads 👍

2 minutes ago, Nexuss said:

I was just about to say @zsde deserves an award for his patience.He has been the most helpful in both of your threads 👍

No one is perfect in life and We all have tested the patience of even the ones we love

this gentleman shows maturity and kindness 2 things some people do not have 

Have a lovely day