Portable solar panel.

[Gate54]

I was wondering if it is possible to use a portable solar panel inside the front window of my caravan to keep the battery charged over winter whilst it is in storage.
The reason I ask is twofold:
I would prefer the portable option as living in the North East the sun is very low at this time of year so it would not make much sense to put a fixed one on the roof. The front window faces South and there is nothing in the way to cast shadows.
The second reason is that I normally take the battery out over winter and charge it at home. Yesterday I put the battery back in the van as I was taking it for a service and I really struggled to get it back in place due to a back issue and not being able to kneel down (a different issue). Because the caravan is German it does not have a conventional battery box and the battery is fixed under the seat - hence the difficulty in getting it in. I have usually managed this previously but my back issues are not going to get any better.
If it is possible would it be ok just to connect using crocodile clips or would I have to disconnect one of the terminals first?
TIA

 

[JTQ]

Before others contradict my view let me say it is "possible", but IMO with some real reservations.

It will work better if it has an unrestricted view, a view not interrupted by the window frame, drapes & shading caused by the moulded in bends in the plastic.
Being a German van it might have a large one piece front window and this will help.
However, its performance will be way lower then if outside, so light is not coming through the plastic.

It can be connected, ideally via a basic solar controller, with in line fuse, straight onto the battery via "croc-clips".

If you don't need much to keep the battery healthy, then that "not much" might be available. I would be tempted to place it outside if that is at all an option.