AC or DC coupled batteries: what changes?
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With DC coupling, the battery connects to the direct-current side of a suitable inverter. With AC coupling, storage has its own battery inverter connected to the home's alternating-current installation. Neither label alone confirms efficiency, backup capability or permission to connect.
Match the arrangement to the existing equipment
An AC-coupled system can allow the existing PV inverter to remain. A DC-coupled system needs a compatible battery interface and control arrangement. Confirm actual model support, voltage ranges, communication and firmware rather than treating either architecture as universally interchangeable.
Compare the complete conversion path during charging and use, together with device consumption and operating limits. A single efficiency figure may not describe all energy flows.
Design control and backup together
The system must measure the required flows and coordinate charging, export limits and household demand. During an outage, compatibility between the PV inverter and the backup supply becomes a separate question.
Specify switching, phases, circuits, power and restart behaviour. Include changes to the switchboard, protection, distribution documentation and warranties when comparing complete retrofit prices.