I’ve bought this Dehumidifier off Amazon recently  as I’ve had a habitation service done recently and there is a high reading in one of the panels.

http://www.amazon.co.uk/gp/product/B00DFYWUJW/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1

It comes with a 12v DC and 240 volt AC lead and power supply and draws 60 watts.

This is what it condensed in a couple of hours. I’d like to leave it on permanently but it is too much of a drain on the leisure battery overnight.
The control panel does shut down on low voltage and the solar panel recharges it to 13.2 by midday.

At this time of year the cab glass is prone to a lot of condensation.