This guide applies the smart grid interoperability reference model (SGIRM) process (IEEE Std 2030-2011) to energy storage by highlighting the information relevant to energystorage system (ESS) interoperability with the energy power system (EPS). The process can be applied to ESS applications located on customer premises, at the distribution level, and on the transmission level (i.e., bulk storage). This guide provides useful industry-derived definitions for ESS characteristics, applications, and terminology that, in turn, simplify the task of defining system information and communications technology (ICT) requirements. As a result. these requirements can be communicated more clearly and consistently in project specifications. This guide also presents a methodology that can be used for most common ESS projects to describe the power system, communications, and information technology (IT) perspectives based on the IEEE 2030 definitions. From this framework, a seemingly complex system can be more clearly understood by all project stakeholders. Emerging cybersecurity requirements can also be incorporated into the framework as appropriate. Additionally, this guide provides the templates that can be used to develop requirements for an ESS project and goes through several real-world ESS project examples step by step.