When running the inverter, a minimum battery charge will be preserved by a “power save” setting in the inverter that emits a small alarm telling you to charge the batteries. From the point of that alarm, assuming you are not running a lot of appliances at the same time, you can charge your batteries to the point that will allow you to return to normal usage in 30-40 minutes (do not stop charging at that point). If you run the batteries right down with the inverter off, you may need to charge them for up to 2 hours before you can return to normal use.
The battery system holds 9600 watts of power and the answer to the question depends on what all you are using to recharge and what you are running. If you run nothing in the coach you can recharge with just the engine alternator/generators at a rate of up to 3500 watts per hr. If you are plugged in to a 110 volt electrical outlet, you can also be adding another 1400 watts and hour. The solar panels will also be adding up to 245 watts per hour depending on the amount of light available to them. As you can see there are many variables and the choices are yours depending on what you want or need to do. Everything you run in the coach or attached to it will reduce the number of watts going into the batteries. Information on their consumption is usually available on the backs or bottom of most electrical equipment/appliances.