Hi @Craig and Leanne , you must have a solar controller for charging your battery when using solar panels. The controller is usually attached to back of panel and it is just a matter of connecting across the battery terminals. Better types are sold separately and require the controller on back of panel to be bypassed. Wiring DOES NOT go through any other device - just straight across the pos and neg terminals. Lots of info on this in earlier postings.
Charging from your car is also possible directly to battery with tug's alternator regulator controlling voltage/charging output. But note that the last method is not really that efficient as some later tugs have regulators that cut out when voltage is too low to get a FULL charge into deep cycle battery. Also be aware that different battery types (Gel or AGM) need different charging requirements. What type of battery is your van battery?? Also have a read of @Drover 's article on battery charging just recently.