My mum (at my suggestion) got a small folding solar panel to keep on her car's dashboard, since (like so many older people) she doesn't do enough mileage to keep her battery going!
Recently, we found that when off-grid in the van at New Year, we had to be careful about using the blown-air heater as it was draining the leisure battery. So I decided to order a panel like my mum's, to plug in and pop through the skylight when necessary. I got it from
http://www.solartechnology.co.uk/solar-panels (not being a big Amazon fan)
It was only around £25, and arrived promptly. Unfortunately, the "cigar-lighter" plug was damaged on arrival, so (without much optimism!) I e-mailed the firm. They got back to me straight away (evening too!), and put a replacement cable and plug in the post.
So if you see anything on their website which might be of use to you, I can strongly recommend their customer service!
Too soon to say whether the unit does the job I want it for, but I'll keep yoou posted.
Facebook
Twitter