TC 120 - Electrical Energy Storage (EES) systems

IEC 62933-4-2:2025 defines the requirements for evaluating and reporting the negative impact on the environment caused by the failure of a cell, flow cell, battery or flow battery in the accumulation subsystem of a battery energy storage system (BESS).
The batteries within this scope used in a BESS are classified according to the type of their electrolyte. These electrolyte types are aqueous, non-aqueous or solid.
The environmental impacts directly caused by the failure of other components of the BESS are not within the scope of this document.

IEC TR 62933-2-201:2024 focuses on the necessity of using repurpose and reuse batteries in BESS. This document also illustrates, through case studies from various countries, how repurpose and reuse batteries are regulated as per legislation. Furthermore, business examples of BESS using repurpose and reuse batteries are investigated and issues derived in terms of both the design, manufacturing, testing, operation, and maintenance of BESS, considering the anticipated future deployment of BESS

IEC 62933-5-1:2024 specifies safety considerations (e.g. hazards identification, risk assessment, risk mitigation) applicable to EES systems integrated with the electrical grid. This document provides criteria to enable the safe application and use of electrical energy storage systems of any type or size intended for grid-integrated applications. This document can be applied to all EESS technologies, but for requirements specific to electrochemical EES systems, reference is also made to IEC 62933-5-2. This first edition cancels and replaces the first edition of IEC TS 62933-5-1 published in 2017. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to IEC TS 62933‑5‑1:2017:
a) Revising “should” statements to “shall” statements for all requirements and move some “should” statements clauses to Annex B for informative purposes.
b) Update standard references (normative).
c) Update definitions and add or remove definitions where necessary.
d) Revise criteria in Clause 6 and Clause 7 to be actionable and add standard references where necessary.
e) Revise Clause 8 for more thorough test method and criteria, add tests where necessary.
f) Add markings and instruction criteria.
g) Revise Annex A to add technology safety information on gravitational and thermal EESS.
h) Add Annex B and Annex C for safety considerations for EESS and test method for mechanical EESS.
i) Add informative list of standards and update bibliography.

IEC 62933-1:2024 defines terms applicable to electrical energy storage (EES) systems including terms necessary for the definition of unit parameters, test methods, planning, installation, operation, environmental and safety issues.
This terminology document is applicable to grid-connected systems able to extract electrical energy from an electric power system, store energy internally, and provide electrical energy to an electric power system. The step for charging and discharging an EES system can comprise an energy conversion.
This second edition cancels and replaces the first edition published in 2018. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) addition (with revision) of the entries developed during the edition 1 stability period and, therefore, included only in other IEC 62933 parts;
b) addition of the entries developed during the edition 1 stability period and published in this document for the first time;
c) complete revision of the entries already present in edition 1.

IEC TR 62933-4-200:2024 describes aspects on reduction of greenhouse gas (GHG) emissions associated with electrical energy storage systems (EES systems), and presents current practices, research activities and related researches in each country.
This document is intended to be used by those involved in design, development and use of EES systems, the grids and the renewable energy sources in the grids, where various applications, including but not limited to long term ones (peak shaving, load levelling, backup power, etc.) and short term ones (frequency regulation, renewable energy stabilization, etc.), are considered.

IEC 60050-631:2024 gives the general terminology applicable to electrical energy storage systems, as well as general terms pertaining to specific applications and associated technologies. It has the status of a horizontal publication in accordance with IEC Guide 108.
This terminology is consistent with the terminology developed in the other specialized parts of the IEV.
This horizontal publication is primarily intended for use by technical committees in the preparation of IEC publications in accordance with the principles laid down in IEC Guide 108.
One of the responsibilities of a technical committee is, wherever applicable, to make use of horizontal publications in the preparation of its publications.

IEC 62933-4-4:2023 describes environmental issues when reused batteries are considered for a BESS.
It provides details and requirements for identifying and preventing environmental issues in each life cycle stage, i.e., from the design to the disassembly of such reused batteries in a BESS.

IEC 62933-5-3:2023 applies to those instances when a BESS undergoes unplanned modifications. Such modifications can involve one or more of the following:
- changes in energy storage capacity;
- changes of chemistries, design and manufacturer of the accumulation subsystem;
- changes of a subsystem component using non-OEM parts,
- changes to the mode of operation,
- changes of the installation site, or
- changes in an accumulation subsystem due to an installation of reused or repurposed batteries.
Any such modification can impair the original state of safety of the BESS.
This document complements IEC 62933-5-2, which relates to the overall safety aspects of a BESS. The requirements covered by this document are applied in addition to the requirements in IEC 62933-5-2 in accordance with each situation.

IEC TS 62933-3-2:2023 provides the requirements for power intensive and renewable energy sources integration related applications of EES systems, including grid integration, performance indicators, sizing and planning, operation and control, monitoring and maintenance. The power intensive applications of EES systems are usually used to improve the dynamic performance of the grid by discharging or charging based on corresponding control strategies. The renewable energy sources integration related applications of EES systems are usually used to mitigate short-term fluctuation and/or to keep long-term stability. This document includes the following applications of EES systems:
– frequency regulation/support;
– grid voltage support (Q(U)) (“volt/var support”);
– voltage sag mitigation;
– renewable energy sources integration related applications;
– power oscillation damping (POD).

IEC TS 62933-3-3:2022 provides requirements, guidelines and references when EES systems are designed, controlled and operated for energy intensive, islanded grid and backup power supply applications. In energy intensive applications, the EES system provides long charge and discharge phases at variable powers to the supported grid or user equipment. In islanded operation, the EES system provides energy to the islanded grid and coordinates other power generation systems in the islanded grid. In backup power supply and emergency support, the EES system provides energy to the internal grid or a set of emergency loads when the main grid power supply is not available.

IEC TS 62933-2-2:2022(E) defines testing methods and duty cycles to validate the EES system’s technical specification for the manufacturers, designers, operators, utilities and owners of the EES systems which evaluate the performance of the EES systems for various applications. The following items are covered in this document. The energy storage devices and technologies are outside the scope of this document:
application;
performance testing methods;
duty cycles for specific application.

IEC TR 62933-2-200:2021(E) presents a case study of electrical energy storage (EES) systems located in electric vehicle (EV) charging stations with photovoltaic (PV) power generation (PV-EES-EV charging stations) with a voltage level of 20 kV and below. EES systems are highlighted in this document because they are a desired option to make the charging stations (especially the high-power fast charging stations) grid-friendly, improve the self-consumption of clean energy generation, and increase the revenue of stations. In this application, EES systems show excellent performance by running in a variety of available operating modes, such as peak shaving, power smoothing, load tracing, time-of-use (TOU) price arbitrage, and ancillary services. The general duty cycle is recommended based on the summary of the operation characteristics of the EES systems.

IEC 62933-5-2:2020 primarily describes safety aspects for people and, where appropriate, safety matters related to the surroundings and living beings for grid-connected energy storage systems where an electrochemical storage subsystem is used.

IEC/TS 62933-3-1:2018(E) is applicable to EES systems designed for grid-connected indoor or outdoor installation and operation. This document considers
necessary functions and capabilities of EES systems
test items and performance assessment methods for EES systems
requirements for monitoring and acquisition of EES system operating parameters
exchange of system information and control capabilities required

IEC 62933-1:2018 defines terms applicable to electrical energy storage (EES) systems including terms necessary for the definition of unit parameters, test methods, planning, installation, safety and environmental issues.
This terminology document is applicable to grid-connected systems able to extract electrical energy from an electric power system, store it internally, and inject electrical power to an electric power system. The step for charging and discharging an EES system may comprise an energy conversion.

IEC 62933-2-1:2017 focuses on unit parameters and testing methods of EES systems. The energy storage devices and technologies are outside the scope of this document. This document deals with EES system performance defining:
unit parameters,
testing methods.  The contents of the corrigendum of January 2019 have been included in this copy.

IEC TS 62933-4-1:2017(E) describes environmental issues associated with electrical energy storage systems (EES systems), and presents guidelines to address the environmental impacts to and from EES systems including the impacts to humans due to chronic exposure associated with the mentioned environmental impacts.

IEC TS 62933-5-1:2017 specifies safety considerations (e.g. hazards identification, risk assessment, risk mitigation) applicable to EES systems integrated with the electrical grid.
This document provides criteria to foster the safe application and use of electric energy storage systems of any type or size intended for grid-integrated applications