Thinking maybe purchasing a solar panel for the van and having it fixed on the roof.
What make and wattage would be suitable for keeping the leisure battery topped up over winter and for using on sites without electric hookup.
This can be largely dependent on your anticipated use when off EHU too. You need to consider how high your demands are for 12v use (TV use, phone/laptop chargers etc, type of lighting).
The efficiency of a panel fixed to the roof isn't great due to it's angle in relation to the sun, but will be greatly reduced during the winter months. While fleck2 above is happy with his 40w panel, I would encourage a 100w panel for reliable all year round use. I fixed a 100w panel to the roof of our former van and this ran all systems very well during the summer and adequately during the winter. A decent MTTP charge controller suitable for the panel is required too, which controls battery charging. These are superior to the cheap and cheerful 'pulse' controllers often bundled with panels on (for example) fleabay.
There's pro's and con's with roof mounting and many will say it's a no-no, but I found it convenient, secure and functioned well with a decent sized panel.
The O.P seems to be asking two questions - a charger for keeping the battery 'topped-up' over the winter and for use on sites without EHU?
Dependant on where the 'van is kept/used/stored over the winter, I would have thought that a much small panel would be required as perhaps only the alarm will be drawing any power?
For use on sites without EHU, how long is a piece of string? There are so many factors to consider that a precise answer is almost impossible.
My advice would be to go for the largest panel you can afford with an 80w panel being the smallest size to be considered.
Think carefully about where you want the panel fitted and why. A smaller panel may suit you if you are happy to have it located on the ground and which you can 'follow the sun' during the day. Not only that, you may be able to use it for other uses ie to power a domestic shed light etc when not out caravanning.
As the Op is talking of having if fixed on the roof, then more than ever with the labour costs involved I push to go for a panel of worth while size.
Panels now are "quite" cheap, the more so if sourced over the internet, and as already stated there is little logical point going for much less than 80 to 100Watts for a roof fixed application.
In winter, being horizontal is far from ideal so you need to over egg on capacity. Sun angles are low, periods of adequate sun are short, tree etc shadows are much more of an issue and grime, bird droppings whilst unattended all take a disproportionate toll on actual yield.
Come the summer and a clean this size and located panel should yield plenty of power for off EHU sustained use; unless one is very profligate with TV etc usage.
I've just bought a 100w kit to install in my transit lwb van. I use the van for camping as well as towing the caravan and I plan to run 2 x 85ah leisure batteries. I'll be powering a couple of ham radios, led lighting, charging phones, iPads etc, and a 12v cool box.
I will be Installing it it when the weather Improves and am looking forward to it. I should state if you are having one or two leisure batteries inside a van make sure they are 'sealed' batteries so they won't leak and dangerous fumes.
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Topic: Solar panels
