I think the relatively high VDC reading is normal, and represents the "available" voltage should it be needed to create current flow of electrons. The voltage varies with solar presentation during the day, as David alludes to. The panel is not a storage device like a battery, but can supply some minimal current during the time it is absorbing solar energy, and can act as a charger to the battery banks. Your solar controller protects from overcharging, and on most coaches provides battery charging even when both battery banks are switched off, which is why to avoid arcing one has to work at night, in a building with little overhead lighting, throw a tarp over the panel, or pull a controller fuse when removing battery connections with switches off and unplugged from park power.
Joel