Wire and Fuse size question - Schematic review

[Foxwalk]

Hi everyone. I'm looking to clarify a few parts of my system before completing my first install on a off-grid house we've been building for the past two years. I'm attaching two pictures here of schematics I've drawn up. I'll add some of the specific questions next to each attachment, but if in general something looks wrong or weird - PLEASE let me know! Thank you all in advance for taking the time to respond to me. Without the help of friends and strangers, building our dream of living off grid would be a lot more difficult, so thank you deeply.

Overview:
1470W 24v solar panels. (Three 490W panels)
9,600W battery bank (4 200Ah 12v lifopo4 batteries)
3000W victron inverter 24v
150/60 Victron MPPT charge controller

Firstly, here is my battery schematic. I want to run them in 24V I've been told to fuse the battery bank and I'm wondering how I calculate the fuse size, what type to use, and where it should be located? The way I have the batteries configured is what the manual says, I looks unusual to me, but it's what it says to do. I'm aware I want to keep wire lengths equal.


Secondly, here is the schematic of my panels on the roof wired to the charge controller. All three panels are identical. I installed 20A fuses on each panel in two places (one on the roof and one in the combination box) I realize this may be redundant and might be a rookie mistake, but it's already installed unless there's something dangerous with it, I wont change it. 1. My questions are: Are 20A fuses the appropriate size? 2. Is my charge controller sized appropriately? (I think I've maxed it out, but is there anything dangerous about it?) 3. What size wire should I run from the combination box to the charge controller? (about 20' distance)

 

[upnorthandpersonal]

how I calculate the fuse size, what type to use, and where it should be located?

In principle, you size the fuse based on the wire - traditionally, a fuse protects the wiring from melting. However, I tend to pick a fuse based on the maximum current I ever intend to draw, and add 25% on that. So if I have a 100A load and never intend to go over that, I pick a 125A fuse, even if the wire could be rated for much more.

You want to fuse each battery pack in parallel. So if you have two strings of 24V batteries in parallel, you fuse each string. You put the fuse as close as possible to the battery, on the positive terminal (or both positive and negative, if you have that in your rules).

I personally always use Class T fuses (and currently investigating BS88 high speed British standard fuses) - but they tend to be expensive. For 24V, you should be able to use MEGA fuses.

Are 20A fuses the appropriate size? 2. Is my charge controller sized appropriately? (I think I've maxed it out, but is there anything dangerous about it?) 3. What size wire should I run from the combination box to the charge controller? (about 20' distance)

You should select the fuse size based on the current a single panel (or string) can deliver, + 25% or so. The reason is that these fuses are there to prevent a high current from going through a damaged panel, where this current is provided by the other panels. This is also the reason you only need to fuse panels when you have more than two (or two strings) in parallel.
Standard 4mm² or 6mm² PV cable will do fine.

 

[AHTrimble]

Fuse and wire sizing that can't be beat: https://www.explorist.life/wire-sizing-calculator/

 

[Foxwalk]

Hi again - I messed up on the battery diagram. The manual actually states to do the following (I used the wrong manual, doh!). However, I am wondering if I can modify it for a cleaner system, which is the second picture. I don't see an issue with it bc all the connections are the same but I just want to double check with someone.