First off, and important for safety, the carbon monoxide sensors have expiration dates (usually posted on the front, and normally lasting about 5-6 years) yours expired in 2007.
If 7.9 is you battery voltage, you have a problem. Are you currently plugged into shore power with that reading?
EDIT: On you Mark controller, you can slide the switch down one notch so it sits on "array current" - that would show you how much Solar is being absorbed - depending on the amount of Sun hitting the panel, you should see some voltage recording - at least you'll have an idea if its working (how much solar do you have on the roof?).
I would also suggest you flip your breakers to "off" position when you are not using the Van.