Comparative analysis of grid code recognition of energy storage in Southeast Asian single-buyer electricity systems

Rapid growth of variable renewable energy (VRE) is not only increasing operation challenges but also motivating wider deployment of energy storage systems (ESS). However, regulatory readiness for ESS deployment can be assessed in part by the extent to which grid codes explicitly recognize ESS and specify technical and operational obligations. Meanwhile, in single-buyer systems, ESS performance and economics depend less on market signals and more on centralized planning, dispatch decisions, and contract design, which create higher risks of underutilization and limited service stacking. Motivated by the lack of systematic review on ESS acknowledgement in grid codes, especially in single-buyer systems, this paper presents a comparative analysis of ESS acknowledgement and ESS-relevant clauses in publicly available grid codes of five Southeast Asian single-buyer countries: Cambodia, Indonesia, Malaysia, Thailand, and Vietnam. The analysis compares ESS resource classification, frequency and active-power operation requirements, voltage and reactive-power requirements, and ancillary-service participation provisions. The results show substantial differences in ESS regulatory maturity, ranging from the absence of explicit ESS recognition in Cambodia and most Indonesian grid-code provisions to dedicated ESS definitions and operational requirements in Malaysia, Thailand, and Vietnam. The findings suggest that explicit ESS recognition provides clearer operational and technical treatment of storage resources within single-buyer electricity systems and may help support more consistent implementation of ESS-related obligations and services.