Hi, Gary,
I have been using a solar panel for about 5 years. I simply made a Connecting lead from Twin Red and and Black Accesory type flex. I attatched a short length to the Live and Neutral of the Battery, to this I fixed the socket side of a connector type Plug and Socket. I used the 3 Pin type as the unused off set Centre Pin avoided the problem of reverse polarity. The other end of this ie. The Plug I attatched to quite a long length of identical Flex and then to the Solar Panel. Which in my case already had a plug and socket attatched. As said previously this allows the long Flex to be removed both from the Battery end and also from the Panel and coiled inside the Battery Box. In use the Flex passes through the cut out in the Battery Box Door normaly used by the Mains Lead. Allowing me to lock it. The Long flex allows me to position the Panel in the best position to catch the Sun even when the Awning or the 'Van would otherwise put it in the Shade. I did consider using the "s" Type plug and Socket but it took up too much space inside the Battery Box. Obviously if you go down this route you can wire it how you wish so long as you use the same Pins on either end and only use it for this purpose. I bought the Flex and plug from Road pro. See On line Shop.
Regards Eddie from Nottingham.