Guidelines on Safety Best Practices for Battery Energy Storage Systems
With the accelerating of energy transition worldwide, the surging expansion of energy storage system (BESS) plays the crucial role in supporting green power system. In 2024, the global cumulative installed capacity reached 150 GW: China reached 62 GW, Europe presented 35 GW, and US added approximately 10 GW.
Given numerous market alternatives, participants such as developers, manufacturers, service providers, and all stakeholders in the value chain need to make informed decisions and ensure additional safety measures are implemented.
Choosing the standard battery
In terms of safety, it is essential to distinguish between primary safety (measures taken to prevent accidents from occurring) and secondary safety (how to better control and manage hazards after an incident occurs). Fundamental safety is directly related to the battery or the cell itself.
There are various types of batteries and each with its own advantages. The most critical factor is whether the battery complies with IEC62619 standard. Users should select the batteries based on the requirements outlined in the section titled Secondary cells and batteries containing alkaline or other non-acid electrolytes. Safety requirements for secondary lithium cells and batteries, for use in industrial applications.This section specifically addresses battery safety and serves as a key reference for ensuring secure operation.
Ensuring safe integration of battery modules, racks, and enclosures
For modules and racks, ensuring the batteries meet UL1973 and IEC62619 standards. Batteries passed the UL9540A certificate indicate they have undergone rigorous testing that simulates thermal runaway events to verify that flames will not propagate.
Choosing the qualified BMS and EMS
The mandatory first step to ensuring the highest level of safety is to use safe and compliant batteries, while monitoring the batteries’ work is equally critical. This is the reason that Battery Management System (BMS) should be deployed: ensuring the battery operation remains within its limits. The BMS must be certificated according to the IEC61508 standard, for electrical, electronic, and programmable electronic safety-related systems.
The BMS generates a substantial amount of data, which is read and stored locally by the Energy Management Software (EMS) and regularly backed up to a secure cloud-based system. All data can be used for analytical purposes to detect potential battery irregularities or deviations at an early stage and to optimize system performance.
Pilot Technology collaborates with MIT research teams, assembling senior experts in artificial intelligence, battery technology, and power systems to develop an AI + Battery + Power integrated learning framework. This initiative has achieved a fundamental breakthrough in early warning capabilities for sudden thermal runaway failures. The algorithms are continuously updated and validated using real-world operational data from over 10 million battery cells, combined with expert diagnostic experience. This enables end-to-end intelligent operation and maintenance recommendations. By comprehensively analyzing historical data, the system delivers customized optimization strategies tailored to the unique characteristics of each energy storage site — implementing a “site-specific approach” for thousands of facilities.
Compartmentalization for Improved Fire Incident Control
Users should install the BESS batteries in robust cabinets that are isolated from one another. This helps prevent fire incidents from spreading to adjacent battery cabinets.
Deploying batteries in separate, fire-resistant enclosures aids in controlling potential fires. The highly fire-resistant cabinet structures provide essential thermal insulation, which minimizes auxiliary energy consumption required to maintain the batteries within a specific temperature range (typically between 20°C and 23°C), regardless of external temperature conditions.
Selecting qualified fire detector and extinguishing system
Compartmentalizing battery cabinets provides a passive method of enhancing safety, while active fire suppression systems offer another layer of protection. The goal of a fire suppression system is to prevent a battery fire from spreading to adjacent units—potentially stopping a small incident involving a few cells from escalating into a large-scale fire that could damage the entire energy storage system or, worse, the entire site. A standard fire detection and suppression system typically consists of smoke and heat detection sensors integrated into an aerosol-based fire extinguishing system, featuring automatic activation.
Pilot's BESS utilizes an integrated control and suppression system that combines a cabinet-level, non-pressurized fire suppression unit (including a controller) with a non-pressurized perfluorohexanone extinguishing device. This integrated approach provides dual-level active and passive protection—at both the pack and cabinet levels.
The outlet of the cabinet-based suppression unit is connected to piercing valves via high-pressure hoses and quick-connect fittings. In the event of thermal runaway in any battery pack, a multi-sensor detector transmits an alarm signal to the suppression unit, which then activates the corresponding piercing valve. Once triggered, the system releases perfluorohexanone extinguishing agent through quick-connect pipelines and pack-level nozzles, directly targeting the affected battery pack.
Utilizing Deflagration Panels to Ensure Personnel Safety
The physical safety of personnel is paramount. Even when the site is secure, maintenance staff may work in proximity to the system to perform upkeep and routine inspections. In the event of a fire or explosion, these employees could be near the battery energy storage system. To protect their safety, deflagration panels are installed to direct any explosive force upward. This ensures that personnel working in the area are shielded from lateral blast effects.
Providing Action Plans for Emergency Responders
During an incident, the actions of emergency responders may not always be straightforward or universally applicable, as they can vary depending on the energy storage system and local conditions. Therefore, it is essential to develop a site-specific emergency response plan and collaborate closely with local emergency response teams.
Implementing an "Emergency Stop" Function
If the EMS, BMS, or any other safety equipment detects a security issue or battery abnormality, the BESS must shut down immediately or undergo a controlled shutdown. It is also essential to have a manual emergency stop function that can be activated by operators or emergency responders.
Detecting Electrical Isolation Faults
Most batteries are electrically isolated from the ground. Advanced insulation monitoring equipment compliant with the IEC 61557 standard must be used to ensure that the insulation integrity does not deteriorate or develop a short circuit to the ground.
Ensuring Compliance with Key Safety Standards such as IEC and UL
In the United States, battery energy storage systems must comply with the NFPA 855 standard to mitigate potential hazards. According to IEC requirements, these systems must also be designed in accordance with IEC 62933-2, which specifies safety requirements for grid-integrated energy storage systems.
Ensuring the Battery Energy Storage System is Equipped with a Circuit-Break Switch
To ensure operational safety, the battery energy storage system must be equipped with all necessary electrical disconnection devices, such as load-break switches, to guarantee safe isolation during maintenance operations.
Ensuring System Compliance with Electrical Safety Standards
Compliance with all relevant IEC and UL electrical safety installation standards( such as IEC 60364 or NEC Article 706 in North America) must be verified through an advanced fuse protection system—particularly those standards protecting equipment against short circuits between polarities.
Pilot Technology's active safety system integrates preventive design, multi-tier early warning, and staged fire response: utilizing LFP batteries with optimized AC bus architecture and modular distributed design to minimize risks; implementing multi-level monitoring (voltage/current/resistance for seconds-level alerts, temperature for minutes-level protection, and gas detection for 30-minute pre-flame warnings); and employing progressive fire suppression including aerosol release, pack-level perfluorohexanone injection, and external water connections to cool, isolate oxygen, and prevent reignition.
Safe Transportation of Battery Energy Storage Systems
Lithium-ion batteries are classified as Class 9 hazardous materials for transportation. Battery energy storage systems must be transported by air, sea, rail, or road in accordance with the UN 38.3 standard.
FAQs
Q1:What standards should a utility-scale BESS comply with to ensure safety?
A: A compliant BESS should adhere to international and regional standards such as IEC 62619 for battery safety, UL 9540A for thermal propagation testing, NFPA 855 for fire safety (in the U.S.), and IEC 62933-2 for grid integration safety.
Q2: How can thermal runaway propagation be prevented in a BESS?
A: Propagation can be mitigated using compartmentalized fire-resistant enclosures, cabinet-level aerosol fire suppression systems (e.g., perfluorohexanone-based), and batteries certified under UL 9540A to resist flame spread.
Q3: What role do BMS and EMS play in enhancing BESS safety?
A: The Battery Management System (BMS) monitors cell-level parameters to prevent over-operating conditions, while the Energy Management System (EMS) analyzes data for early anomaly detection. Both should comply with IEC 61508 for functional safety.
Q4: Why is an emergency response plan critical for BESS installations?
A: Emergency plans ensure site-specific protocols are in place for firefighters and operators, including manual emergency stop functions and deflagration panels to direct explosive forces safely upward.
Q5: What are the key considerations for transporting battery energy storage systems?
A: BESS units must be shipped as Class 9 hazardous materials in compliance with UN 38.3 standards, covering safety tests for air, sea, rail, and road transportation.
