A BESS container stores energy in batteries and discharges it when the project requires it. In large-scale installations, thousands of cells operate in unison, and a localized failure can generate heat, flammable gases, smoke, and material damage.

In 2026, thermal runaway is one of the risks monitored by owners, investors, financiers, and insurers. In the context of insurance for photovoltaic parks and BESS storage systems, the topic may seem technical at first glance, yet the logic is easy to follow: an event originating in a single cell can affect a module, a container, and—under certain conditions—nearby equipment.

In this article, you will learn:

• what thermal runaway means and how it begins;
• what insurers look for in a BESS project;
• what types of policies can protect the investment;
• how insurance relates to testing, monitoring, and the emergency response plan.

What Thermal Runaway Means for a BESS Container in 2026

BESS stands for Battery Energy Storage System. Commercial and industrial installations frequently utilize lithium-ion batteries, which consist of cells, modules, cooling systems, electrical equipment, and a control system.

Thermal runaway occurs when a cell begins to generate more heat than it can dissipate. The reaction accelerates, internal components degrade, and the temperature rises at a rate that is difficult to control.

Causes analyzed by EPRI include manufacturing defects, overvoltage, excessive current, high temperatures, and physical damage. A problem affecting a single cell may remain isolated or transfer heat to neighboring cells.

The process can generate flammable gases and hot particles. If these gases mix with oxygen in the presence of an ignition source, fires or explosions may occur. Thermal runaway and fire are related yet distinct events: the former describes the thermal reaction within the cell, while the fire may ensue subsequently.

The level of risk depends on battery chemistry, module design, manufacturing quality, temperature control, and the method used to detect anomalies.

How an incident can spread within a BESS system

In a BESS container, factors such as the spacing between modules, internal barriers, ventilation, and detection systems influence how an incident unfolds. Protective measures aim to rapidly identify the issue and limit the spread of heat or gases.

• Cell monitoring: The system tracks voltage, current, and temperature to identify deviations from operating limits.
• Temperature control: Proper cooling helps maintain the batteries within their design-specified range.
• Inter-module propagation: Heat released by a cell can affect neighboring cells if separation and protection measures do not limit heat transfer.
• Re-ignition: The EPA indicates that lithium-ion battery fires can be difficult to extinguish and may re-ignite hours or even days after the initial event.

In other words, an incident could result in consequences extending beyond the container itself. Power conversion equipment, transformers, cabling, nearby buildings, and grid connection infrastructure could all sustain damage.

What an insurer checks in 2026 before accepting BESS risk

The assessment begins with the project’s technical description. The insurer needs to understand the battery type used, the system manufacturer, the container layout, and the surrounding equipment.

The analysis may cover the battery management system, remote monitoring, smoke and gas detection, temperature control, power supply, unit spacing, and access for emergency response teams.

UL 9540A testing is a recognized benchmark for evaluating fire propagation associated with thermal runaway. The method analyzes behavior at the cell, module, unit, and installation levels. The results can help determine protective measures and the required spacing between equipment.

Key takeaway: A test report does not eliminate risk. It provides information on system behavior and can support a clearer assessment of protective measures.

The insurer may also request details regarding maintenance procedures, alarm history, emergency response plans, commissioning documentation, and protocols for coordination with fire departments or local authorities.

How Leader Team Broker can structure BESS insurance

Leader Team Broker works with local and international insurers—including through a partnership with Lloyd’s of London—to cover photovoltaic and wind projects as well as BESS systems. Our offering is specifically tailored to developers, investors, investment funds, EPC contractors, O&M operators, and financial institutions.

Here is how Leader Team Broker can assist you:

• Construction-phase coverage: CAR (Contractors’ All Risks) and EAR (Erection All Risks) policies can be evaluated for assembly, installation, and commissioning. These cover physical damage to works, materials, equipment, and installations. For BESS projects, the assessment may also include design errors, delays, and third-party liability, depending on the contract structure.
• Operational-phase protection: Once the system is operational, the focus can shift to Property Damage, accidental breakdown, fire, hardware defects, business interruption, and civil liability.

These elements must be aligned with the value of the equipment and the revenue generated by the project.

• Contract and policy analysis: Our company provides consultancy for contract analysis, negotiations, and independent audits of existing policies. Furthermore, we offer access to over 600 specialized products, a response within 24 hours, and the potential to achieve savings of up to 35% through the auditing of existing policies. Specific details are determined for each project.

 

Leader Team Broker Services Complementing BESS Container Insurance in 2026

Thermal runaway must be considered alongside other project risks. An insurance program may comprise multiple policies, each serving a distinct purpose:

• Property Damage: Can cover physical damage to operational equipment, subject to contract terms.
• Business Interruption: Can protect against lost revenue following a loss event that temporarily halts system operations.
• General Liability: Addresses third-party claims for bodily injury or property damage arising from project activities.
• Professional Liability: Covers errors, omissions, or negligence related to design, engineering, and consulting services.
• Cyber Insurance: Can cover specific cyber incidents, security breaches, and operational disruptions affecting connected systems.
• Environmental Liability: Can be evaluated to cover costs associated with pollution, cleanup, and the management of affected materials.

Leader Team also offers the option to assess projects currently in the development, testing, or transport phases. For financed projects, insurance policies and guarantees must be aligned with the requirements of investors, lenders, contractors, and operators.

What a BESS policy can cover and what to check in the contract in 2026

A BESS (Battery Energy Storage System) policy can cover fire, accidental damage, equipment defects, electrical events, cyber incidents, business interruption, and third-party liability. The exact scope depends on the policy type, limits, deductibles, conditions, and exclusions.

Battery capacity degradation must be analyzed separately. The fact that a system delivers less energy over time does not automatically constitute an insured loss. If this exposure relates to a performance contract or obligations to a financier, it must be disclosed prior to the quoting process.

The same principle applies to revenue losses. Estimating business interruption requires knowledge of the waiting period, project revenues, tariffs, sales contracts, and the realistic timeframe for repair or replacement.

Critical point: In 2026, an insurance policy for BESS containers does not replace the facility’s safety plan. Obligations regarding maintenance, monitoring, incident notification, and cooperation with authorities can influence the assessment of a claim.

Before signing, verify the limit for each equipment category, the deductible, the covered territory, the indemnity period, and the conditions applicable to batteries affected by fire or firefighting water.

What to do before and after a BESS incident in 2026

A sound plan begins before the first alarm sounds. The owner must know who monitors the system, who can shut down the installation, who contacts the fire department, and how the incident is reported to the insurer.

Following an alert or a fire, access to the area is permitted only after an assessment by authorities and specialists. In 2026, affected batteries can remain dangerous, even if flames are no longer visible.

Specifically, keep these important tips in mind:

1. Prepare technical information: Keep container plans, electrical schematics, battery data, alarm details, and shutdown procedures in a location accessible to authorized teams.
2. Coordinate the response: Consult fire departments and local officials when planning the response. The EPA recommends preparing procedures in advance for fires, emissions, and the management of damaged batteries.
3. Promptly notify relevant parties: After ensuring personnel safety, notify authorities, your broker, the insurer, and contractual partners, then retain photographs, reports, and documentation regarding the incident.

An incident can incur costs beyond mere battery replacement: cleanup, transportation, business interruption, damage to neighboring properties, and technical investigations. Your insurance plan must account for this reality.

Checklist for Thermal Runaway Risk Assessment and Comparative Analysis for a BESS Container in 2026

How to Properly Select and Manage Insurance for a BESS Container in 2026

Describe the project before requesting a quote: Prepare details regarding system capacity, battery type, number of containers, equipment value, location, project phase, and estimated commissioning date. A clear description minimizes unnecessary back-and-forth and facilitates the comparison of offers.

Separate project stages: Construction, transport, testing, and operation entail different risks. CAR (Contractor’s All Risks) and EAR (Erection All Risks) policies can be considered for installation work, while Property Damage and liability policies become relevant once the system enters the operational phase.

Verify the definition of loss/damage: Request clarifications regarding fire, explosion, hardware defects, capacity degradation, contamination, cleanup costs, and loss of revenue. Terms must align with the limits and deductibles specified in the contract.

Align the policy with lender requirements: Banks and investment funds may mandate specific limits, assignments, guarantees, and indemnity periods. Insurance documentation must align with the obligations set out in financing and operating contracts.

Review the program following modifications: Capacity expansion, battery replacement, cooling system modifications, or connection to different infrastructure can alter the risk profile. Periodic reviews ensure the policy remains aligned with the actual installation.

Ultimately, thermal runaway is a technical risk that must be translated into clear decisions regarding design, operation, and insurance. An owner who documents the system, verifies protective measures, and negotiates appropriate coverage gains a more realistic view of their financial exposure.
For an analysis of the project, contracts, and available options, you can request a personalized quote from Leader Team Broker. In 2026, data regarding the system, project stage, and financier requirements helps facilitate a detailed discussion about insurance for photovoltaic parks and BESS storage systems.

 

References and official sources:

• UL Solutions – https://www.ul.com/services/ul-9540a-test-method;
• U.S. Environmental Protection Agency – https://www.epa.gov/electronics-batteries-management/battery-energy-storage-systems-main-considerations-safe;
• Electric Power Research Institute – https://storagewiki.epri.com/index.php/Storage_Safety;
• National Fire Protection Association – https://www.nfpa.org/codes-and-standards/nfpa-855-standard-development/855;
• Leader Team Broker – https://leaderteam.ro/asigurarea-parcurilor-fotovoltaice-eoliene-sistemelor-stocare-bess/.

Frequently asked questions about BESS insurance offered by Leader Team Broker in 2026

What does “thermal runaway” mean for a BESS container?

Thermal runaway is an accelerated thermal reaction within a battery cell. The cell generates more heat than it can dissipate, causing the internal components to degrade. The process can generate flammable gases, smoke, and high temperatures. If the reaction affects neighboring cells, the incident can spread to the module or container level. Temperature detection, battery control, and protection systems can limit the consequences.

Can Leader Team Broker analyze insurance for a BESS project under construction?
Yes, the offer presented by Leader Team Broker includes an analysis of BESS projects currently in the development, testing, or transit phases. For the construction period, CAR (Contractors’ All Risks) and EAR (Erection All Risks) policies can be evaluated; these cover physical damage to the works, materials, equipment, and installations. The final structure depends on the specific project, contracts, investment value, suppliers, contractors, and the financier’s requirements.

What can a BESS policy cover regarding thermal runaway and fire?

A BESS policy can cover physical damage, fire, accidental damage, hardware defects, business interruption, civil liability, cyber incidents, and certain environmental costs. Actual coverage depends on contract terms, limits, deductibles, and exclusions. Thermal runaway must be addressed within the facility’s general assessment, alongside measures for detection, cooling, separation, and emergency response.

What documents does the insurer require for a BESS container?

The documentation package may include the system’s technical description, battery type and manufacturer, site plan, electrical schematic, maintenance procedures, monitoring systems, emergency response plan, and test reports. Information regarding equipment value, project revenues, EPC and O&M contracts, protection measures, and emergency team access may also be requested.

Can BESS insurance also cover loss of revenue?

Yes, business interruption can be considered as part of the BESS insurance program. Coverage addresses financial losses resulting from the facility shutting down following an insured loss, subject to the limits and timeframes stipulated in the contract. A realistic assessment requires data on project revenues, sales contracts, repair times, waiting periods, and equipment replacement costs.