I've installed 600W of solar panels on the roof.  They are very thin 'flexible' panels which only weigh 1.5Kgs per panel, unlike the traditional 'rigid' panels which generally weigh about 17 or 18Kgs each.

The panels are held down by industrial double sided tape I got from Germany, SikaFlex on the leading edge, as well as rivets in each corner.

The panels are connected up in 3 serial/parallel pairs. This boosts the voltage for each pair of panels to 42v.

All six panels feed into a distribution box. Inside the box is an 8A slow blow temperature sensitive fuse for each of the 3 pairs of panels.

There are two options from this box:

1) All 6 panels feed the 12 volt batteries.

2) 2 panels go to the 24v batteries and 4 panels go to the 12v batteries.

The MPPT controllers are on the opposite side of the wall (see next photo).

The little controller shown at the bottom is for a separate extra mobile 130W panel which can be moved to a sunny spot if the truck is parked entirely in shade. This supplies the fridge in a separate circuit from all the other circuits and is protected by an 11.1v cutout.

On the other side of the wall from the batteries are the controllers and an inverter. The 2 units on the right are GSL 30A MPPT controllers, which convert the higher voltage solar supply (it comes in at 42v) into 12v/24v as appropriate.

The inverter, on the left, is 600W and connects to a double power point in the cabin.

All of these units will be hidden underneath the seats that have yet to be built.

The inverter feeds a double power point in the cabin with a meter to monitor how much power is being used.

It has a low voltage cut-out so even if you leave something on by mistake it won't flatten the battery bank completely.

Note that all the power points are Double Pole, which means that both the live AND the neutral pins are switched.  In a domestic power point, only the live pins are switched.