In 2010, the organising committee for the first IFBF conference identified the need to develop standards to support the growing flow battery industry. As a result, several companies and individuals formed a CENELEC workshop and CWA 50611: Flow batteries – Guidance on the specification, installation and operation was published in April 2013. Building on this work many flow battery standards have since been approved and published.
Standards matter to this industry for a practical reason. A flow battery is permanent infrastructure, frequently grid-connected, and increasingly installed close to buildings, industrial processes and critical facilities. The questions asked by a network operator, an insurer, a planning authority or a lender are answered by reference to standards, and a technology without them is difficult to specify, to permit and to finance.
This page explains how the relevant standards are organised and sets out the current regulatory position, followed by a full list of national and international standards relevant to flow batteries.
How flow battery standards are organised
Standards specific to flow batteries. The IEC 62932 series, Flow battery energy systems for stationary applications, is the international standard written specifically for this technology. It is published in three parts: Part 1 covers terminology and general aspects, including the formal definitions of a flow cell and a flow battery; Part 2-1 covers performance, general requirements and test methods; Part 2-2 covers safety requirements.
Appendix B of Part 2-2 specifies a test regime addressing matters including stack fluid leakage. Work presented at the Forum has observed that these tests provide a sound basis for evaluating the performance and safety of flow battery systems but may not be sufficient for every application, and additional testing is often required for specific deployments. CENELEC CWA 50611, the workshop agreement that originated with the IFBF community, remains a reference for specification, installation and operation.
Standards for energy storage systems generally. Flow battery installations are also governed by standards written for electrical energy storage as a whole. The IEC 62933 series covers vocabulary, unit parameters and test methods, planning and performance assessment, environmental issues, and safety for grid-integrated systems. IEC 62485 addresses safety requirements for secondary batteries and battery installations, and IEC 61427 covers batteries for renewable energy storage in off-grid and on-grid applications.
Safety and installation. In North America, UL 1973 is the safety standard for batteries in stationary applications, UL 9540 covers energy storage systems and equipment as a joint Canadian and United States standard, UL 9540A is the test method for evaluating thermal runaway fire propagation, and NFPA 855 governs the installation of stationary energy storage systems. Compliance with these is frequently a condition of permitting in North American jurisdictions and is increasingly requested elsewhere.
The characteristics of flow batteries are relevant to how these standards apply. Aqueous electrolytes with low flammability, operation at ambient temperature and pressure, and the absence of thermal runaway in the form associated with lithium-ion cells change the nature of the hazard, but do not remove the requirement for containment, ventilation and spill management. IEEE 1578 addresses electrolyte spill containment specifically, and IEEE 1635 covers ventilation and thermal management.
National standards. China has the most developed body of national standards specific to vanadium flow batteries, covering terminology, general specification, test methods, safety requirements and electrolyte, together with test methods for bipolar plates, ion conducting membranes, single cells and electrodes. South Korea has published KS C 8547 covering performance and safety tests for redox flow batteries in energy storage systems. In Germany, the BattG sets national requirements for placing batteries on the market and for their take-back and disposal.
Certification in practice
Flow battery products have been certified against these standards for a decade. Redox flow batteries manufactured by Sumitomo Electric were the first in the world to obtain UL 1973 certification, in 2015, requiring demonstration of safety against explosion, fire, liquid leakage and destruction. The third-generation stack design of the Invinity VRB-ESS passed testing to UL 1973:2018 and received CSA certification in June 2022. Systems have been designed to comply with NFPA 855 and UL 9540 since at least 2019.
European regulation
The Batteries Regulation. Regulation (EU) 2023/1542 concerning batteries and waste batteries replaced Directive 2006/66/EC and applies across the battery sector, including stationary storage. It introduces requirements relating to carbon footprint, recycled content, performance and durability, labelling and end-of-life management, phased in over several years.
The PFAS restriction under REACH. The proposed restriction on per- and polyfluoroalkyl substances is the most consequential regulatory development currently facing the flow battery industry, because the fluorinated membranes conventionally used in vanadium systems fall within its scope.
A restriction proposal was submitted to the European Chemicals Agency in February 2023. ECHA has since published draft opinions from its Risk Assessment Committee and its Socio-Economic Assessment Committee, and a further public consultation on those opinions closed on 25 May 2026. The final opinion of the Socio-Economic Assessment Committee is expected by the end of 2026, a decision by the European Commission is not anticipated before the third quarter of 2027, and any restriction would not apply before 2029. The draft opinion recommends removing or significantly reducing a number of the derogations contained in the original proposal.
The response within the industry has been to develop membrane alternatives rather than to seek indefinite exemption. Work presented at the Forum covers non-fluorinated membranes including polybenzimidazole composites and hydrocarbon ionomers, together with accelerated methods for assessing long-term membrane stability in vanadium electrolyte, so that candidate materials can be identified early in development.
Work in progress
Electrolyte standardisation. Vanadium electrolyte is not yet covered by an international specification standard, and its standardisation has been identified at the Forum as a key factor in increasing the market share of vanadium flow batteries. A standardised electrolyte would support customer acceptance, bankability and the circular economy, by making electrolyte a fungible commodity that can be traded, leased, recovered and reused independently of the system it was first supplied with. Analytical work on samples of commercial electrolyte has been presented as a starting point for that specification.
The IEC technical committee. Flow battery standards are developed within IEC Technical Committee 21, which covers secondary cells and batteries, through its working group on flow batteries. Members of the International Flow Battery Forum participate in this work.
Taking part
The IFBF encourages all those in the industry to take an active interest in the development of standards, not only for flow batteries, but also those relating to other forms of electrical energy storage and associated equipment. If you wish to participate, you should contact your national committee for standards for further information.
List of standards
Below is a list of national and international standards relevant to flow batteries. Care has been taken in the preparation of this information, but it is not necessarily complete or comprehensive. We thank Jens Noack of Fraunhofer ICT for collating this information and making it available to the IFBF.
Updated September 2026
IEC Standards
| Number | Title |
|---|---|
| IEC 60050 | International electrotechnical Vocabulary (IEV) |
| IEC 62932-1:2020 | Flow battery energy systems for stationary applications – Part 1: Terminology and general aspects |
| IEC 62932-2-1:2020 | Flow battery energy systems for stationary applications – Part 2-1: Performance, general requirements and test methods |
| IEC 62932-2-2:2020 | Flow battery energy systems for stationary applications – Part 2-2: Safety requirements |
| IEC 61427-1:2013 | Secondary cells and batteries for renewable energy storage – General requirements and methods of test – Part 1: Photovoltaic off-grid application |
| IEC 61427-2:2015 | Secondary cells and batteries for renewable energy storage – General requirements and methods of test – Part 2: On-grid applications |
| IEC 62485-1:2015 | Safety requirements for secondary batteries and battery installations – Part 1: General safety information |
| IEC 62485-2:2010 | Safety requirements for secondary batteries and battery installations – Part 2: Stationary batteries |
| IEC 62933-1:2018 | Electrical energy storage (EES) systems – Part 1: Vocabulary |
| IEC 62933-2-1:2017 | Electrical energy storage (EES) systems – Part 2-1: Unit parameters and testing methods – General specification |
| IEC TS 62933-3-1:2020 | Electrical energy storage (EES) systems – Part 3-1: Planning and performance assessment of electrical energy storage systems – General specification |
| IEC TS 62933-4-1:2017 | Electrical energy storage (EES) systems – Part 4-1: Guidance on environmental issues – General specification |
| IEC TS 62933-5-1:2017 | Electrical energy storage (EES) systems – Part 5-1: Safety considerations for grid-integrated EES systems – General specification |
| IEC 62933-5-2:2020 | Electrical energy storage (EES) systems – Part 5-2: Safety requirements for grid-integrated EES systems – Electrochemical-based systems |
| IEC 60079-10-1 | Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas atmospheres |
IEEE Standards
| Number | Title |
|---|---|
| IEEE 2030.2.1-2019 | IEEE Guide for Design, Operation, and Maintenance of Battery Energy Storage Systems, both Stationary and Mobile, and Applications Integrated with Electric Power Systems |
| IEEE 1657-2018 | IEEE Recommended Practice for Personnel Qualifications for Installation and Maintenance of Stationary Batteries |
| IEEE 1679-2020 | IEEE Recommended Practice for the Characterization and Evaluation of Emerging Energy Storage Technologies in Stationary Applications |
| IEEE 1375-1998 (inactive) | IEEE Guide for the Protection of Stationary Battery Systems |
| IEEE 1578-2018 | IEEE Recommended Practice for Stationary Battery Electrolyte Spill Containment and Management |
| IEEE 1491-2012 | IEEE Guide for Selection and Use of Battery Monitoring Equipment in Stationary Applications |
| IEEE 1660-2018 | IEEE Guide for Application and Management of Stationary Batteries Used in Cycling Service |
| IEEE 1635-2018 | IEEE/ASHRAE Guide for the Ventilation and Thermal Management of Batteries for Stationary Applications |
| IEEE 1881-2016 | IEEE Standard Glossary of Stationary Battery Terminology |
| IEEE 946-2020 | IEEE Recommended Practice for the Design of DC Power Systems for Stationary Applications |
| IEEE 1184-2006 | IEEE Guide for Batteries for Uninterruptible Power Supply Systems |
| IEEE 1547.1-2020 | IEEE Standard Conformance Test Procedures for Equipment Interconnecting Distributed Energy Resources with Electric Power Systems and Associated Interfaces |
Other Standards
| Number | Title | Remarks |
|---|---|---|
| CENELEC CWA 50611:2013 | Flow batteries – Guidance on the specification, installation and operation | CENELEC workshop agreement on flow batteries |
| UL 9540 | Standard for Safety – Energy Storage Systems and Equipment | Joint Canadian – United States standard |
| UL 1973 | Batteries for Use in Stationary, Vehicle Auxiliary Power and Light Electric Rail (LER) Applications | |
| NFPA 855 | Standard for the Installation of Stationary Energy Storage Systems | Fire safety standard |
| ISO 15663:2001 | Petroleum, petrochemical and natural gas industries – Life cycle costing | International standard |
| EU Directive 2006/66/EC (replaced by the new Batteries Regulation) | Directive 2006/66/EC of the European Parliament and the council of 6 September 2006 on batteries and accumulators and waste batteries and accumulators and repealing Directive 91/157/EEC | European Commission directive |
| EU Regulation 2023/1542 | Regulation (EU) 2023/1542 of the European Parliament and of the Council of 12 July 2023 concerning batteries and waste batteries, amending Directive 2008/98/EC and Regulation (EU) 2019/1020 and repealing Directive 2006/66/EC (Text with EEA relevance) | European Parliament and the Council Regulation |
| PFAS restriction under REACH | Proposed restriction on the manufacture, placing on the market and use of per- and polyfluoroalkyl substances, submitted to the European Chemicals Agency in February 2023 | Proposal in progress, not yet adopted. See “European regulation” above |
| BattG 2021 | German “Gesetz über das Inverkehrbringen, die Rücknahme und die umweltverträgliche Entsorgung von Batterien und Akkumulatoren (Batteriegesetz – BattG) | German national law |
| UFC 3-520-05 | Stationary and Mission Batteries | US-Military standard |
| UL 9540A | Test method for evaluating thermal runaway fire propagation in battery energy storage systems | |
| KS C 8547 | Redox flow battery for use in energy storage system – Performance and safety tests | Korean standard |
| PNNL-22010 | Protocol for Uniformly Measuring and Expressing the Performance of Energy Storage Systems | |
| CSA F382:M89 | Characterization of Storage Batteries for Photovoltaic Systems | Canadian standard |
Chinese National Standards
| Number | Title |
|---|---|
| GB/T 29840-2013 | Vanadium flow battery – Terminology |
| GB/T 32509-2016 | General specification for vanadium flow battery |
| GB/T 33339-2016 | Vanadium flow battery system – Test method |
| GB/T 34866-2017 | Vanadium flow battery – Safety requirements |
| GB/T 37204-2018 | Electrolyte for Vanadium flow battery |
| NB/T 42006-2013 | Electrolyte for vanadium flow battery – test method |
| NB/T 42007-2013 | Bipolar plate for vanadium flow battery – test method |
| NB/T 42040-2014 | General specification for vanadium flow battery – Abolished 2018! |
| NB/T 42080-2016 | Testing method of ion conducting membrane for vanadium redox flow battery |
| NB/T 42081-2016 | Performance test method for single cell of all – vanadium redox flow battery |
| NB/T 42082-2016 | Test Method for Electrode of Vanadium Redox flow battery |
Common questions
Which standard applies to a flow battery?
The IEC 62932 series is written specifically for flow battery energy systems in stationary applications and covers terminology, performance and safety. It applies alongside the general energy storage standards of the IEC 62933 series and, in North American jurisdictions, UL 1973, UL 9540 and NFPA 855.
Are flow batteries covered by the same safety standards as lithium-ion batteries?
Largely the same standards apply, since they are written for stationary energy storage rather than for a single chemistry. The hazards differ: aqueous flow battery electrolytes have low flammability and the systems do not exhibit thermal runaway in the form associated with lithium-ion cells, but the electrolytes are chemicals requiring containment, ventilation and spill management, which the standards address.
Is there a standard for vanadium electrolyte?
Not at international level. China has published GB/T 37204-2018 covering electrolyte for vanadium flow batteries, and NB/T 42006-2013 covering the corresponding test method. Work towards an international specification is in progress and has been reported at the Forum.
How will the PFAS restriction affect flow batteries?
The proposed restriction covers the fluorinated membranes conventionally used in vanadium systems. No restriction is yet in force; the current expectation is a Commission decision no earlier than the third quarter of 2027 and application no earlier than 2029. Development of non-fluorinated membrane alternatives is well advanced and is reported on at the Forum each year.
IFBF conference papers
Standards, certification and regulation are recurring subjects in the IFBF conference papers, written each year by the presenters at the Forum. A complete list of previous conference papers is available here.