Help! Please Review My Wiring Diagram...

I'm trying to design my electrical system for an off grid camper van. I am a complete newb when it comes to electric so please forgive me. Attached is the first draft of my wiring diagram that I hope you all can make sense of. A few questions I'll propose in advance:
-Coming of my leisure battery I have 4 wires coming off of the negative terminal and 3 coming off of the positive terminal (I may also add an alternator charger in the future which would add 2 more wires). Is this too much coming off the terminals and should I consider wiring it all to a positive and negative busbar beforehand?
-Coming off of the leisure battery, do fuses go before or after an on/off switch?
-I'm not entirely sure of the correct fuses and gauge wire to use on each connection so please look out for this.
Thanks for any and all help,
Nick
Comments
Battery connections, with 2 batteries in parallel, should be made to the positive terminal of one and the negative terminal of the other. This provide equal resistance across the batteries.
I would use breakers instead of fuses, and use them as on/off switches in an emergency.
In general, for household wiring the 3 panels should have a breaker of fuse on each panel. I have no problem with 3 12 volt nominal, panels wired without. The idea is that 2 of the panels would be able to over power the other in case of a short, but with the max of 20 volts the risk of fire in pretty much non existent between the roof of the car and the panels.
I would 'float' the system and not try to ground to the chassis.
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
I'm surprised the forums host doesn't carry them so I'm only going to show a photo of them. Blue Sea has these terminal mount fuses that are IMHO the best protection for your DC wiring . They have a single version as well.
2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.
https://www.bluesea.com/products/2151/Dual_MRBF_Terminal_Fuse_Block_-_30_to_300A
-Bill
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
http://www.armstrongssupply.com/wire_chart.htm
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
For parallel connecting batteries, IIRC there's an argument to be made that using overly large parallel connection wire for very low resistance can be counter-productive.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
I missed that you were using an MPPT CC, your diagram shows parallel wiring, though you say series,
You might be money ahead to use DC breakers and a short piece of Din rail or a small din rail breaker box for both your 'fuse' and switch.
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
Even if your panels have a vmp of 19 volts or above, it will lose much of that during the heat of the day. This is called the Normal Operating Cell Temperature (NOCT)value. While I couldn't find a 100 watt panel to give you for example, you may find they publish the NOCT values for their panels. Since you have 100 watt 12 volt nominal panels, they will have 36 cells. Here is an example of a Silfab panel which has 72 cells so double the voltage. They publish both the STC standard test condition values which is the 'name plate' rating, along side the NOCT values which is what you can expect during the heat of the day.
You can see the normal STC rating is 350 watts at 38.9 volts (with 72 cells) if we use half the value as if it was a 36 cell panel it would have a VMP of 38.9÷2= 19.5 volts, but in reality when hot they will only produce 35 volts as a 72 cell panel, or 17.5 volts (35÷2) as a 12 volt nominal panel. too low to allow a MPPT type charge controller to work properly.
Some manufacturers will publish this information as a minimum input voltage in their manual, so don't. The charge controller will work without the higher voltage, but be unable to convert as much of the extra wattage to usable charging current.
- Assorted other systems, pieces and to many panels in the closet to not do more projects.