Point of connection (PoC / PCC / POI)
The electrical and contractual boundary between a BESS plant and the external electricity network. Called Point of Connection (PoC), Point of Common Coupling (PCC), or Point of Interconnection (POI) depending on jurisdiction. The grid connection agreement defines all technical requirements the plant must satisfy at this point.
In energy storage
Performance guarantees — rated power, energy capacity, reactive power capability, and round-trip efficiency — can be defined at different measurement points: at the DC terminals, at the low-voltage AC bus, or at the PoC itself. Specifying the measurement point matters because cumulative conversion and auxiliary losses across the power train can reduce stated energy capacity by up to 10% between the DC terminals and the PoC.