AC-coupled means that, structurally, the PV grid-tied inverter first converts PV power to AC. The battery then connects to the same AC bus through a separate storage inverter.
Advantages: Suitable for retrofitting existing PV systems — the original PV inverter remains unchanged, and the battery system can be added directly. PV and storage operate relatively independently, offering strong system compatibility and scalability.
Disadvantages: Slightly lower efficiency, more equipment required, and potentially higher system cost and footprint. This is because the typical energy path for charging the battery from PV is: DC (PV) → AC → DC (battery); and for discharging: DC (battery) → AC — involving one extra conversion step.
