Look behind the wall connector and follow the wires:
- They may be connected to nothing (ie: prep'd but not hooked up)
- They may be ran directly to the battery in which case, you need a solar charge controller (cheap and simple to add) between the panels and the wall connector.
- They may be connected with a solar charge controller. Then you just need to connect the solar panel wires to the wall connector.
The inverter/charger (aka: converter) is a separate device with the exception of certain high end models which are highly unlikely to have been included. The charger in this case refers to a device that takes 120v AC power and converts it to 12v DC power to charge the batteries.