connecting 1976 Millard van to solar power

there is a 130ah deep cycle battery, 80w solar panel on roof, all wired to the charge controller

I would wire everything direct from the battery via fuses.

Also make sure pin two in the trailer socket isn't connected. Once you wire the lights to the battery you may also inadvertently connect pin two to the battery. You don't want this

thanks for that. The not so original wiring for the van had the internal lights wired to pin 2, with the negative to pin 3

All old vans were wire that way so you had lights

hi
wiring for trailer lights completely separate to all else
electric brake wiring separate to all else

Old school 12v supply might be present as others have mentioned . Need to rewire these thru a fuse box onto all the accessory lights etc etc

Input to battery
Solar panels connect to controller on the solar terminals
Battery connects to that terminal

Output from battery
Fuse box draws power from battery

Up grade to a 12 pin flat plug ,use the heavy duty pins for brake feed .
----Earths
Combine these on van side then go thru h/duty pin on the 12 pin plug
WIRE THIS TO BATTERY POST --use 8mmsq / 8b&s cable

dctodc charging another subject
dedicated charger or direct connect to altenator

Never run your brake feed in any other pin than pin 5. It is an ADR standard.
The top pins on a 12pin can handle 20amps. 8 guage is about 40 to 60 amps
The whole last part of the above post is vague or just plain wrong! You dont need a 12 pin plug for what you have said you need to do Wil060

Quote "Never run your brake feed in any other pin than pin 5"
Agreed, If someone else needs to tow your van for you they will be doing so not knowing they have no braking on the van. You are a Richard Cranium if you wire the brake through any other pin that does not conform with the Oz standard.
Likewise thieving the reverse signal pin (pin 2) for powering things is not a good idea these days with the availability of 12 pin plugs and Anderson plugs. These days if you do not specify to a tow bar fitter to wire the trailer socket up in a non standard manner then they are likely to wire pin 2 to your brake lights. If you leave the fridge switched to 12 V you will blow the brake light fuse There have been reports of this happening in caravan magazine tow vehicle tests. In one instance the flashing indicators were on the same circuit so they lost the use of those. In another test they lost the use of their power windows. As above this could be a problem for someone if they tow your van to help you out. The other problem is that pin is too light to carry much power (10 A max) and you are likely to weld pin 2 into the socket (it happened to me 25 years ago, that's why I have used 12 pin connectors since then.)

Disconnect the internal power from pin 2 and if in future you wish to supply power from the tug then install connectors that will reliably handle the current.

The idea of power from the solar set up is to give the caravan essentially its own off grid system, I am not intending on drawing power from the tow vehicle at any stage.
The only items running from the battery in the caravan are the lights and later on a new fridge.
The lights, LED's, use minimal power and from what I understand can be run directly from the charge controller load terminals.
Looking at later adding an accessory cig socket, this would be run straight from the battery. This is where i need the advice - do i wire the negative from the accessory socket back to the battery (via a bus bar) or do I earth the negative from the accessory to the caravan body?

cheers

As I said at the top. Everything direct to the battery via a fuse on the positive
You may need to earth the battery to the van depending on were the lights are earthed

hi
Wiring more than 2 braked axles needs a heavy duty pin .
Pins also wear out .
There is even more circumstances to even use more than 1 of these plugs oh god !

No it doesn't. Caravan manufacturers fit tandem axles with 7 pin plug. I personally would use a 7 pin round but under no circumstance should you use the top four pins on a 12 pin for anything other than what they are designated for.