Julie,
You may want to describe how you got the .3 amp current flow measurement with the switches off. If you lifted the plus terminal of the battery bank that feeds the coach and inserted an amp meter in series, that would be a true current flow measurement. Most on board systems use a DC Shunt (low value resistor in series) of some sort and measure the voltage drop across it and the electronics calculates the current value. Sometimes these systems are not accurate at low values but you could measure the current flow at the battery lead to confirm. As Gerald points out there is still a lot going on with the switch off, some systems are tied in anyway. The inverter settings should have inverter "off" to use minimal current in standby. I do not know your monitor system but a +.3 amps may be charging current while a -.3amps would be discharging. This value does not seem like a problem to me and would be overcome by minimal light energy reaching the solar panel. As far as having the batteries professionally charged, that is something that should not be necessary, and I do not see how that could cause discharge unless the batteries were removed for this and put back with some wire attached differently which seems unlikely. I do not think there is much to worry about here with such a low value of discharge. Let us know if you find out how to get back to zero....
Later Ed
