Important considerations for Lithium-ion battery energy storage systems (BESS) in South Africa - By Marika du Plessis

By Dr Marika du Plessis, MCD Consult

There is a world-wide focus on increasing our reliance on green energy and South-Africa’s adoption of green energy technology is impressive. Undoubtedly, load-shedding and the increase in cost of electricity have been important factors that added to the need and willingness for South-Africans to adopt this technology. Many households are the envy of their neighbours with their shining lights in the dark hours of power cuts.

This technology has many benefits and is truly helpful for its users but the fire risks associated with these battery energy storage systems (BESS) are often overlooked to the detriment of emergency personnel, insurance companies, businesses and, most importantly, the public at large. In a white paper released in 2024 by the Electric Power Research Institute (EPRI) a sharp decrease in failure incidents is reported for grid-scale BESS systems globally, despite the exponential growth in the number of installations world-wide. The main reason cited for this decrease in failure rate is “lessons learned from early failure incidents that have been incorporated into new designs and best-practices”.

Unfortunately, due to poor regulation, testing and reliability of quality of system components, South-Africans largely do not enjoy the benefits of the “lessons learned” globally, and we can still expect a much higher failure rate, injuries and losses locally. That is the bad news. Fortunately, the good news is that this situation can be remedied by implementing and mandating some wellestablished guidelines for BESS systems that are now available internationally. Furthermore, to implement some basic and minimum fire safety requirements for BESS installations would be quite easy in South-Africa, and it will be a start in the right direction.

Most people have watched spectacular fires from Lithiumion battery products online, so the concept of thermal runaway, the ejection of flammable and toxic gasses, and the almost instantaneous large jet flames are firmly established in our minds. The potential deflagration risk when these gases are accumulated in an enclosed space is less well-known however, and most users of BESS systems are totally unaware of this risk. There have already been a few large residential (and industrial) explosions internationally, caused by larger groupings of Lithium-ion cells typically found in electric vehicles (EVs) and home BESS systems.

Locally, a BESS deflagration occurred in Vanderbijlpark, South-Africa, in January 2025, where the occupants of the house sustained injuries ranging from mild to serious burns. The owners of the property described the incident “like a bomb went off in their house” and that even the roof lifted. Due to the large energy density in Lithium-ion batteries and their inherent fire and explosion risk, Lithium-ion batteries have been classified in South-Africa as Dangerous Goods, Class 9, in SANS 10228 at least since 2010. Most Municipalities specify a maximum limit in weight that should not be installed without a dangerous goods certificate. Although, most home installations do not reach this limit, businesses are often close to or over this threshold. Depending on the manufacturer, a 30-kWh energy capacity BESS system might already require a dangerous goods certificate. Since this legislation is already in place, the Fire Service can easily start regulating the larger installations and thereby improve their own emergency responder safety and that of the public at large.

The current best practice guideline available for BESS installations of any size is NFPA 855 (free to view at nfpa.org if you register on the website). This standard gives simple and clear guidance on location requirements for BESS installations, maximum allowed stored energy based on a certain location, and critical size and separation requirements to limit fire spread. Just enforcing these sections of NFPA 855, as part of issuing a dangerous goods permit, will already unlock at least some minimum fire safety benefit from lessons learned internationally. NFPA 855 also gives easy to apply guidelines on the same topics for one- and two-family dwellings and townhouse units that, if applied, will reduce the life safety risks associated with home BESS systems significantly.

Ideally, every BESS installation in South-Africa should be required to comply to the complete NFPA 855 standard. That being said, there are especially two requirements in this standard that makes compliance of current installations in SouthAfrica challenging. The first is the requirement of NFPA 855 that only UL 9540 listed equipment may be installed and the second is that explosion control is required, in general, for installations exceeding 80 kWh. (A typical home installation may be in the range of 5 to 20 kWh.)

UL 9540 is the primary compliance standard available for BESS systems as a whole. This standard ensures complete compliance and compatibility of all the components used in a BESS system. Some suppliers in South-Africa already sell products compliant to this standard, and mandating compliance for products sold in our market should be considered. If we look at the majority of products available in our market, however, they do not comply to any fire safety standard at all, not at cell level, module level or systems level. So, while aiming for system level compliance is preferred, we should at least require cell level compliance as a minimum. Most countries require basic cell level fire compliance to either UL 1642 or IEC 62619 for BESS systems as a minimum for products sold in their market. If South-Africa does not implement at least a requirement for this basic cell level fire compliance, we cannot expect the same level of fire safety that most other countries enjoy in the foreseeable future.

In South-Africa there are numerous installations where local shipping containers are re-purposed for BESS containers which do not have any explosion control. Emergency responders should, therefore, always rely on work procedures to safeguard them against possible deflagrations. A clean agent or any type of gaseous suppression system installed in containerised BESS systems, including aerosol type suppression systems, may in some circumstances increase the risk of a deflagration. Emergency procedures should therefore always consider this possibility. Best practice currently for firefighters is to set-up at a distance away from a burning/off gassing BESS container system, evacuate the public if applicable, and just let the unit burn itself out. Water should only be used to cool surrounding areas to limit fire spread and should preferably not be sprayed on the flames of the BESS system. This philosophy would not be possible in every situation, but if it can be followed it may reduce the impact of the incident to a minimum and eliminates further incidents and possibly injury as much as possible.

Businesses, the public and emergency workers cannot count on proper fire engineering design of BESS products in the South-African market yet. As we work towards better fire safety compliance requirements, however, we can implement immediate steps to increase the life safety of users. Enforcing the NFPA 855 requirements on the location, maximum allowed stored energy, critical size and separation for BESS systems on as many installations as possible would be a valuable first step. Also, educating installers and users to look for compliance to UL 1642 or IEC 62619 (cell fire safety standards) as a minimum for home installations and UL 1973 (module fire safety standard) and/ or UL 9540 for larger installations, will support those suppliers and manufacturers that takes the lives and property of their clients in terms of fire safety seriously.