RE: Solar Panel
If you have what I think you have (based on the specs you sent and the fact
that it is VW) it was/is intended to keep a fully charged battery topped off
during long periods of inactivity but only under ideal conditions, that is,
with plenty of Sunlight.  IIRC it is meant to be plugged into the cigarette
lighter socket.  Theoretically it could be used to charge or maintain other
devices.  But be careful, the peak voltage could be to high for some things
especially if not designed to handle the higher voltage.