DIY junction box

[borosane]

Hi all,

after looking for a larger junction box online, i wasn't able to find any that suits my need for a number of ports for wires.
Since i decided that i will not have a junction box on every panel, i decides to put all wires from 8 panels into 1 box.

Here is rough schema.
junctionbox-001.jpg

Please share your thoughts on this.
Any comment is appreciated.

[Mike90250]

I can't figure your schematic out. If you have more than 3 parallel circuits, you need breakers or fuses. Diodes - for what ?

[borosane]

Thanks for pointing this. I see the error now.

I had initial idea of of joining 2 panels in series, and make 4 pairs in such way (which would give me 40V 8A per pair).
Then those 4 arrays/pairs connect in parallel which would give me 40V 32A in total. - that's why i have left 4 bypass diodes by mistake.

Later i changed my mind and thought it would be easier to join 4 panels in parallel and then join those 2 array in series - but diodes i forgot from previous plan.

Here is the new schematic but i'm not sure i got it correct either. Please take a look:
jbox 001.jpg

Why do i need breakers or fuses ?
Thank You on reply.

[borosane]

Please, can you at least post a link to some tutorial or article about fuses in solar panels ?

[Mike90250]

....

Why do i need breakers or fuses ?
Thank You on reply.

one panel ---> charge controller & Loads---> FUSE ---> Battery +

adding a 2nd panel in parallel to the first no PV array fuses needed

BUT when you add a 3rd parallel panel, then if 1 panel gets a fault, the power of 2 other panels feeding into the fault can start a fire. So more than 2 parallel panels, needs protection. At least a fuse, but a DC breaker is nice because it can occasionally be used as a switch for testing purposes.
The fuses or breakers get installed near the panels in a Combiner Box which is a common solar supply item.SolarPanelFire_1c.jpg