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.

 

[Beardy]

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

This is exactly what I do (with a few changes).
I bought a 25w kit from Eco-Worthy (via ebay) in June last year. Over the summer the panel sat under the roof light - I made two battens that fit in the slots and the solar panel sat on top of them. This was very successful until around November when I found that I wasn't getting much charge as the sun wasn't getting high enough so I moved the panel to a south facing side window.

JTQ is absolutely correct, the output from the solar panel is much diminished compared to being outside. My windows (and roof light) are tinted which cuts down the light getting through, and when under the roof light the panel is recessed by a couple of inches so the sun has to be higher in the sky to eliminate shadows on the edges of the panel. I also have a battery voltage logger attached so that I can see the state of the battery and when it's been charging. I'd guess that in December / January, 4 out of 5 days I get minimal charge, sometimes pretty much zero, but on a clear bright day (like yesterday) the battery was fully charged again.

Rather than trying to get wires from the solar controller (inside the caravan) to my battery box, I found the +12v and 0v wires inside the caravan and tapped into them with an inline fuse. It sounds like you may be able to get to your battery much easier.

Here is the kit I bought, and the battery monitor.

Edit: Just to add that I don't have an alarm so I'm only looking to compensate for the battery's 'self discharge'.

 

[Gate54]

Thanks for your replies. The van does indeed have a one piece front window so this should help. I'm not keen on leaving the panel outside the van as it could be blown over by the wind. The storage site is quite large and does have people going in and out regularly, so I wouldn't want it on the ground where people might drive into it.
The battery is under a seat near the front of the van so I don't need to consider how to get the wires to it.
I was considering something like a 100w panel with a solar controller.
There is of course the alternative of getting out in the van bit more over winter, which I try to do but due to circumstances I haven't been able to use it since October except to take it for a service on Wednesday (it's still under warranty - just).

 

[JTQ]

Don't get carried away with the panel's Wattage, focus on its physical size.
A too large a panel, where one or more edges, or corners don't get an obstruction free exposure to the light, will suffer a compromised yield.
However, compromised by a percentage way more than the "lost" area percentage.
A panel, [or two] that fits without incurring light obstructed bits would be best. If two panels, make them a pair and wire in parallel.

The capacity of panel you are thinking of must be used with a controller [ideally a quality one], or you seriously risk damaging the van's GEL technology battery. Gel, assuming it has an OEM specified battery.

 

[Mel]

The people who have a Caravan near ours at the storage compound do exactly this. I have no idea how well it works but presumably it does.
BTW, At our current storage site it is clearly acceptable but at our previous storage site the owners insisted that the leisure battery was disconnected. Hence it may be worth checking with the storage site before spending money.
Mel