When I hear coupling I think inverter to inverter One usually responsible for managing the battery storage. Is the PV power sent all the way to the batteries as DC ? then it's DC coupled, Is the PV power converted to AC (Micros/String inverters ) then BACK to DC to the batteries > AC coupled. I like to break up a vendors device into what you are getting inside ( PV MPPT - get the solar DC power, DC Charger 24/48V or AC to DC Charger - monitor and charge a battery, Inverter - Convert DC into AC for loads, Transfer switch - detect power and move source or loads from path A - path B like ac1 -> ac2 in, AC Sync Grid or Offgrid - Maintain Phase with Utility or provide a Sync for GT devices ... XW/Quattro/SolArk It's been a big help in my keeping all the vendor products "strait" Like XW -> NO MPPT ( extra device + extra DC charger), Fronius String inverter is MPPT + Inverter (NO DC Charger, no transfer) , Sol-Ark/GroWatt ?? ) -> all parts hybrid. It's a mixed bag vendor by vendor what functions are "inside the box" A bit of a messy place since they are all developing so fast. But is does help with comparing $$$ apples to apples