I think you might have cracked it Steve and Debbie.

That's the Schaudt booster that controls the charge from the tow vehicle to the battery. My two fuse holders are more conventionally in line and fixed to the floor.

This is the wiring diagram for my Reich Economy Light mover: only one big fuse to feed the mover control panel, not two separate onesIMG_0044.JPG - Bild entfernt (keine Rechte)

Would help if there was a side on picture of the wiring: cant see if both black and both reds are connected to a single terminal each or if they are connected to separate terminals.

Jackie,
We have the same blade fuse holders on our Triton. Not sure why they are there but they are evidently part of the original Eriba spec. To fit a solar panel I found it easiest to connect the panel to a solar panel charge controller - EBay, about £10-15 - connected in turn directly to the battery terminals. You apparently need the controller to make sure that the PV panel only charges the battery, rather than draining it. This was a twenty minute job and works well.
Richard

Partially correct Richard.

A correctly built solar panel should have a diode to prevent the battery discharging if the solar panel isn't generating but theres no guarantee that all do.

The main reason for a controller though is to ensure the panel doesnt raise the voltage of the battery too high so that it "cooks" the battery. (through over-voltage)

A flat / discharged battery will have a low voltage and the solar charger will push up its output to the battery to raise the battery's charge. As the battery becomes charged its voltage will rise and the controller will reduce its output voltage until is just slightly above that of the the fully charged battery (to maintain a so-called trickle charge to replace natural battery losses when its not being used)

Applying a solar panel direct to a discharged battery wont do the battery any harm for a short period since the voltage of the battery will pull down that of the solar panel output. If left connected for too long however as the battery voltage increase so does the output of the solar panel (which could theoretically reach 17V or more even its rated as a 12V solar panel) which could lead to applying too much voltage to the battery

So back to the original post, if these wires go directly to the battery terminals they could indeed be used to connect a controller to.