I have here a PowerFilm 10 Watt F15-600 Solar Panel, and attached to the panel is this connector:
The male end attached to the panel has a little green rubber gasket on it and the female end goes to a 12V female "port" into which you can put a 12V male cigarette adapter.
Notice how there is a gap in the right-side of the male plug and how there is a corresponding slot in the female one so that the polarity won't be reversed. Also, the clip won't attach if it was reversed.
I am just wondering if there's a place I could get more of these female ends so I can make more water-resistant attachments to the solar panel. The socket is a pretty good design, but I wonder if it is a proprietary design.