Battery Storage Safety in 2026: What Investors Need to Consider During Due Diligence

Sept. 15

Written by the Logic Energy Editorial Team

The main risk isn't the cell itself, but the design. What testing certifications battery storage investors should require in 2026—from UL 9540A to thermography.

The short answer

Battery storage safety depends less on cell chemistry than on planning, installation, and location: According to EPRI data, poor integration and construction quality are the cause of failure in about 36 percent of cases, not cell defects. The probability of fire in modern PV storage systems is low—about 0.0049 percent per year. For investors, verifiable test certifications are key: UL 9540A, a fire safety concept, LFP cell chemistry, and regular thermography.

No issue unsettles investors in PV storage systems quite like the risk of fire. Media reports about exploding battery storage systems make headlines but say little about professionally designed systems. This article is intended for investors evaluating battery storage projects—the “Guide to Battery Storage as an Investment” provides the revenue framework.

Why PV Storage Systems Catch Fire: Thermal Runaway

In short: Fires in battery storage systems are caused by thermal runaway—a self-reinforcing overheating of individual cells. According to EPRI, however, assembly and integration errors are the cause in about 36 percent of cases, not cell defects. The probability of a fire is about 0.0049 percent per year.

Fires in battery storage systems are caused by thermal runaway—a self-reinforcing overheating of individual battery cells. Triggers include cell defects, overcharging, mechanical damage, or faults in the battery management system. The statistics are crucial for investors: According to analyses by EPRI and TWAICE, poor integration, installation, and construction quality are the primary cause in about 36 percent of cases. At the same time, the failure rate of large-scale storage systems fell by about 97 percent between 2018 and 2023, and research institutes such as RWTH Aachen estimate the probability of fire in modern home storage systems at only about 0.0049 percent per year—roughly fifty times less likely than the general risk of a house fire.

Battery Chemistry: Lithium-Ion, Lithium Iron Phosphate, or NMC?

In short: Lithium iron phosphate (LFP) batteries are more thermally stable than NMC cells: They require higher temperatures to trigger thermal runaway and do not release oxygen. By 2026, over 95 percent of home energy storage systems will use this cell chemistry; many insurers explicitly require it.

Cell chemistry has a significant impact on battery storage safety. Lithium iron phosphate (LFP) batteries are considered more thermally stable than NMC cells: they require higher temperatures to experience thermal runaway and do not release oxygen when they decompose. In addition, LFP batteries offer a long service life, with approximately 4,000 to 10,000 charge cycles. Lithium-ion batteries are the most widely used storage technology; LFP is the standard for stationary Li-ion batteries—over 95 percent of home storage systems will use this chemistry by 2026.

Battery Management and Installation Location at the PV System

In short: A battery management system (BMS) monitors the temperature, voltage, and state of charge of each cell and protects against overheating. The installation location is just as important: a dry, cool, well-ventilated room, at least one meter away from flammable materials, with an operating temperature of 5 to 25 degrees.

Two practical factors determine operational safety. The first is the battery management system (BMS): It monitors the temperature, voltage, and state of charge of each battery cell, thereby protecting against overheating and malfunctions. The second is the installation location: Battery storage systems should be installed in a dry, cool, and well-ventilated room—such as a utility or equipment room—at least one meter away from flammable materials. The optimal operating temperature is between 5 and 25 degrees Celsius. Smoke detectors and professional installation by certified contractors are part of basic safety measures.

Standards and Regulations 2026

In short: Different regulatory standards apply depending on the size of the system. VDE-AR-E 2510-50 applies only to residential and small commercial systems; for commercial and utility-scale storage systems, UL 9540A, NFPA 855, and the Model Building Code 2025 apply, supplemented by VdS 3145 in its revised version from June 2025.

Relevant Standards and Regulations for Battery Storage Systems
Set of Rules	Scope / Purpose
VDE-AR-E 2510-50	Security Requirements: Private Individuals and Small Businesses Only
UL 9540A	Fire Spread Test Method (No Certificate)
NFPA 855	Installation Standard for Stationary Storage Systems
IEC 62933-5-2	International Safety Requirements (Revised December 2025)
VdS 3145	PV and Storage Requirements, Revised Edition, June 2025
Model Building Code 2025	Minimum distances based on system energy and chemistry
Source: DKE, UL Solutions, VdS/GDV, Model Building Code 2025

Important: The frequently cited VDE-AR-E 2510-50 applies explicitly only to residential and small-scale commercial battery storage systems, not to large-scale storage systems. For commercial and utility projects, UL 9540A, NFPA 855, and building code requirements apply. The revised version of VdS 3145 requires a non-combustible base, minimum clearances from combustible materials, and fire-resistant partitions for indoor installations.

What Insurers Require

In short: Insurers have effectively become the de facto safety standard. In exchange for affordable premiums, they require LFP cell chemistry, a compliant fire safety plan, installation in accordance with standards, as well as documented UL 9540A test data and independent thermal management audits. Involving the insurer early on reduces project risk.

Insurers have become a de facto safety standard. To offer competitive premiums, they are increasingly requiring LFP cell chemistry, a compliant fire safety plan, installation in accordance with standards, as well as documented UL 9540A test data and independent audits of thermal management. By involving the insurer early on, you can clarify these requirements before they become a project risk—insurability is a key factor in every calculation for a storage investment.

Thermography of a PV System and Storage Unit

In short: Infrared thermography—often drone-assisted—detects hotspots, defective cells, and substrate defects noncontact during operation. A small system costs around 200 euros; larger ones range from 300 to 800 euros. Inspections are recommended every two years, as well as at the time of commissioning and before the warranty expires.

Thermography is an effective and often underestimated tool. Infrared cameras—often mounted on drones—detect hotspots, defective cells and strings, as well as substring faults, non-contact during operation, before they cause damage or fires. The costs are manageable: A small rooftop system can be inspected for around 200 euros, while larger systems cost between 300 and 800 euros. This topic is currently gaining prominence: According to a technical publication from July 2026, substring and soldering defects are on the rise in half-cell modules, which increases the risk of fire—thermography during commissioning and operation is therefore considered mandatory. It is also a key O&M component for systems with integrated battery storage.

An Objective Assessment of the Bentwisch Case

In short: On July 5, 2026, a battery storage system overheated in a wooden shed in Bentwisch near Rostock; three firefighters sustained minor injuries in the explosion, and the damage totaled approximately 40,000 euros. The cause is still under investigation—this incident serves as a reminder to exercise caution, not to panic.

This case highlights two things: the real risk posed by improperly installed small-scale storage systems—and the contrast with a professionally planned system that includes a fire safety plan, structural separation, and monitoring. It is unwise to jump to conclusions about the system technology as long as the cause remains unknown. That is precisely why the chain of verification in due diligence is so important.

Due Diligence Checklist

Investors should request concrete evidence before making an investment:

UL-9540A test report or equivalent large-scale test for the storage system used
Fire Safety Plan in accordance with the State Building Code, including proof of clearances
VdS-3145 compliance, particularly when applying for insurance
Cell chemistry certification (LFP preferred) with a data sheet on thermal runaway behavior
BMS Specification with Cell Isolation, Redundancy, and Early Gas/Smoke Detection
Fire Suppression and Ventilation Plan (Deflagration)
O&M Contract with a Monitoring and Thermography Schedule
Proof of insurance, including coverage for EMS/BMS integration
Track Record and Creditworthiness of the Manufacturer and Integrator

Important Note: This article is intended solely for general informational purposes and does not constitute investment, tax, or legal advice. Information regarding returns, income, proceeds, lease payments, and costs consists of sample calculations or market observations as of the date indicated and does not constitute a guarantee of future results; the actual values that can be achieved depend on location, system design, contract terms, and market developments. Information regarding standards and incidents is current as of September 2026. Professional planning is required for the specific design of fire protection and safety measures. For your specific situation, please consult a licensed tax advisor, attorney, or investment advisor. All information is provided without warranty. As of September 21, 2026.

Planning a Storage Project Safely

Are you considering an investment in battery storage and want to thoroughly evaluate the safety and fire protection certifications? We design storage systems using LFP cell chemistry, a fire protection concept that complies with standards, and a documented chain of verification.

Go to the contact form Battery Storage for Commercial Use

Frequently Asked Questions (FAQ)

What is the probability of a fire occurring in a battery storage system?

Low: Studies estimate it at about 0.0049 percent per year. The failure rate of large-scale storage systems has dropped by about 97 percent since 2018. According to EPRI, the main cause of incidents is assembly and integration errors, not cell defects.

Is LFP really safer than NMC?

Yes, generally speaking. Lithium iron phosphate batteries require significantly higher temperatures to undergo thermal runaway and do not release oxygen, which fuels the reaction. Over 95 percent of home energy storage systems will use this cell chemistry by 2026.

Where should a battery storage system be located?

In a dry, cool, and well-ventilated room, such as a utility room or mechanical room, at least one meter away from flammable materials. The optimal operating temperature is between 5 and 25 degrees Celsius. Smoke detectors and proper installation are part of basic safety measures.

As an investor, what standards should I be familiar with?

International: UL 9540A (fire test), NFPA 855 (installation), and IEC 62933-5-2 (revised December 2025). National VDE-AR-E 2510-50 (residential and small commercial use only), VdS 3145, and the Model Building Code 2025 with its spacing requirements.

What exactly do insurers require?

Typically, this includes LFP cell chemistry, a compliant fire safety plan, installation in accordance with standards, documented UL 9540A tests, and independent thermal management audits. Involving the insurer early on reduces project risk and often lowers the premium.

How is thermography used in storage systems?

Infrared cameras detect hotspots, defective cells, and substring defects noncontact during operation, before damage occurs. Inspections are recommended every two years, as well as during commissioning and before the warranty expires.

Conclusion: Security is a matter of implementation

By 2026, battery storage safety will primarily be a matter of build quality, not just cell technology. The probability of fire is low, failure rates have dropped significantly, and the main cause lies in assembly and integration. Investors who require LFP cell chemistry, a well-designed battery management system, the right installation location, UL 9540A certification, a fire safety plan, and regular thermographic inspections can minimize the actual risk.

The "Photovoltaics Industry" guide shows how storage systems are integrated into an overall project; the "Battery Storage" guide provides the revenue framework, and our page on commercial PV battery storage systems covers the basics.

References

Logic Energy Editorial Team https://www.logicenergy.de/