Its not clearly stated what type of controller that is being used for charging batteries from the solar panels. The PWM controller will decrease the power going to the battery(ies) by reducing the voltage from the solar panels (~20V) to the same as the battery (12V) therefore the 190 watts from the solar panel will only feed 114 watts to the batteries. The MPPT controllers transforms the extra volts into additional amperage to realize the full190 Watts.
Is the controller an MPPT or the cheaper PWM? Is this an option? GoPower offer both types.