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UL Certifications for Battery Systems
Rahul Jalthar

UL Certifications for Battery Systems: A Complete Guide

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Battery Energy Storage Systems (BESS) are becoming essential in today’s energy landscape. Whether for renewable integration, grid stability, or backup power, ensuring the safety and reliability of these systems is critical. This is where UL certifications for battery systems play a crucial role.

UL (Underwriters Laboratories) is one of the most trusted global safety certification organizations. Its standards verify that battery energy storage systems meet strict safety, fire prevention, and performance requirements. For project developers, manufacturers, and operators, understanding these certifications is not optional—it’s necessary.

In this guide, we’ll explore key UL standards such as UL 9540, UL 9540A, UL 1973, and others. You’ll also learn how these certifications impact compliance, insurance, and deployment.

At Sunlith Energy, we help businesses navigate energy storage safety and compliance while building reliable battery solutions.

Why UL Certifications Matter for Battery Energy Storage

1. Safety and Risk Mitigation

Battery systems, if not designed properly, can pose fire hazards or thermal runaway risks. UL standards ensure that systems undergo rigorous testing to minimize these risks.

2. Regulatory Approval

Most jurisdictions require UL-certified equipment for permitting. Without it, projects can face delays, redesigns, or rejection.

3. Market Trust and Bankability

Investors, insurers, and end-users trust certified systems. A BESS with UL certifications demonstrates credibility and long-term reliability.

👉 Related Read: Complete Guide to Battery Energy Storage Certification

Key UL Certifications for Battery Systems

UL Certifications for Battery Systems

UL 9540 – Standard for Energy Storage Systems and Equipment

UL 9540 is the primary certification for energy storage systems. It evaluates the safety, performance, and construction of complete systems, not just individual components.

  • Covers batteries, Power Conversion Systems (PCS), control systems, and enclosures.
  • Required for grid-scale, commercial, and residential BESS installations.
  • Ensures systems meet fire safety and electrical safety standards.

Why it matters: Without UL 9540, your BESS may not receive local authority approval.

👉 Learn more about Energy Storage PCS and how it integrates into certified systems.

UL 9540A – Test Method for Evaluating Thermal Runaway Fire Propagation

UL 9540A is not a certification itself but a test method. It assesses how thermal runaway in one cell can propagate through modules, units, and installations.

  • Provides data on fire propagation and suppression.
  • Often required by fire marshals and building authorities.
  • Supports UL 9540 certification by demonstrating safe design.

👉 Explore our article: UL 9540A Test Method Explained

UL 1973 – Batteries for Use in Stationary and Vehicle Auxiliary Power Applications

UL 1973 focuses on individual battery modules and packs used in stationary systems.

  • Tests electrical, mechanical, and environmental safety.
  • Covers BESS, telecom backup, and EV auxiliary batteries.
  • Often a prerequisite before seeking UL 9540 certification.

Example: A lithium-ion module must first pass UL 1973 before being integrated into a UL 9540-certified system.

UL 1741 – Inverters, Converters, Controllers

Since BESS includes PCS (Power Conversion Systems), UL 1741 applies to inverters and related power electronics.

  • Validates PCS for interconnection safety with the grid.
  • Ensures compatibility with renewable energy and microgrids.
  • Critical for hybrid solar + storage projects.

👉 Read our guide: PCS vs Inverter – Key Differences

UL 1974 – Evaluation for Repurposing Batteries

As second-life batteries become more common, UL 1974 helps ensure repurposed cells are safe for reuse.

  • Evaluates used EV or industrial batteries for BESS applications.
  • Supports sustainability by extending battery life.
  • Ensures recycled batteries meet minimum safety standards.

Benefits of UL-Certified Battery Systems

  1. Regulatory Compliance – Smooth project approvals and grid interconnection.
  2. Enhanced Safety – Reduced risk of fire, explosion, and system failure.
  3. Market Acceptance – Easier financing and insurance.
  4. Long-Term Reliability – Certified systems undergo rigorous life-cycle testing.
  5. Future-Proofing – UL standards evolve with technology, ensuring systems stay relevant.

Challenges in Achieving UL Certification

  • Cost and Time: Certification requires extensive testing, which can delay projects.
  • Design Changes: If a component fails testing, redesign may be necessary.
  • Complex Standards: Navigating multiple UL standards can overwhelm new manufacturers.

This is where industry partners like Sunlith Energy provide support—helping companies design systems aligned with certification requirements from day one.

UL Certifications for Battery Systems

How Sunlith Energy Helps with UL-Compliant Solutions

At Sunlith Energy, we ensure that every battery system we design aligns with UL safety and certification standards. Our approach includes:

  • Design Consulting: Guiding OEMs and EPCs on compliance from the design phase.
  • Testing Support: Preparing systems for UL 9540, UL 9540A, and UL 1973 evaluations.
  • End-to-End Solutions: Delivering certified-ready BESS with integrated PCS, battery modules, and fire safety systems.

Whether you’re deploying grid-scale storage, C&I projects, or hybrid solar + storage, our certified solutions meet the highest safety benchmarks.

👉 Learn more about our Battery Energy Storage Systems

FAQs on UL Certifications for Battery Systems

1. What is UL certification for battery systems?

It is a safety and performance evaluation that ensures battery energy storage systems meet global standards for fire safety, electrical reliability, and environmental resilience.

2. Do all BESS need UL 9540 certification?

Yes. For commercial and residential deployment in most regions, UL 9540 is mandatory.

3. What’s the difference between UL 9540 and UL 9540A?

UL 9540 certifies the system, while UL 9540A is a test method used to analyze thermal runaway propagation.

4. How long does certification take?

Depending on system complexity, UL certification can take 6–12 months.

5. Can second-life batteries be certified?

Yes, through UL 1974, which evaluates repurposed batteries for safe use in stationary storage.

Conclusion

UL certifications for battery systems are the foundation of safe, compliant, and bankable energy storage projects. From UL 9540 system-level approvals to UL 9540A fire safety testing and UL 1973 battery-level compliance, these standards ensure that energy storage systems perform reliably under real-world conditions.

As energy storage adoption accelerates, ensuring compliance with UL standards will not just be a regulatory requirement—it will be a competitive advantage.

At Sunlith Energy, we’re committed to helping businesses deploy safe, certified, and future-ready energy storage systems.

Why CE for BESS Matters
Rahul Jalthar

CE for BESS: Complete Guide to Battery Energy Storage Certification

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Battery Energy Storage Systems (BESS) are critical to the clean energy transition, but ensuring their safety and compliance requires more than just good engineering. Certifications like CE for BESS is one of the most recognized marks in Europe, confirming that a product meets essential health, safety, and environmental standards. However, while CE is necessary for entering the EU market, it does not always guarantee complete system-level safety. To build global trust, manufacturers often combine CE with other certifications such as UL and IEC, ensuring stronger compliance, reliability, and market acceptance.

What Does CE Certification Mean for BESS?

The CE mark (Conformité Européenne) is a mandatory certification for products entering the European Economic Area (EEA). For BESS, CE shows compliance with EU directives and harmonized standards.

When a BESS carries the CE mark, it declares conformity with the following directives:

  • Low Voltage Directive (LVD) – Protects against electrical hazards.
  • Electromagnetic Compatibility (EMC) Directive – Prevents electrical interference.
  • Restriction of Hazardous Substances (RoHS) – Limits toxic chemicals in batteries and components.
  • General Safety Directives – Cover risks related to machinery and consumer use.

In essence, CE for BESS confirms that the system has met basic EU safety and environmental requirements, allowing it to be legally marketed and installed in Europe.

What Does CE for BESS Cover?

CE certification for BESS evaluates multiple aspects of product safety. These include:

  1. Electrical Safety – Preventing risks of electric shock, short circuits, and overheating.
  2. Thermal Safety – Assessing insulation, cooling design, and fire prevention.
  3. Electromagnetic Compatibility (EMC) – Ensuring the BESS does not emit disruptive signals.
  4. Environmental Safety – Controlling hazardous substances and ensuring recyclability.

However, CE certification for BESS is primarily based on a self-declaration of conformity. Manufacturers test the product internally or through a notified body, then issue a Declaration of Conformity (DoC).

This process makes CE less complex compared to third-party certifications like UL or IEC, which require independent validation and rigorous lab testing.

Why Do Most Companies Choose Only CE Certification for BESS?

Many BESS companies stop at CE certification instead of pursuing more demanding approvals. The main reasons include:

  • Lower Costs: CE testing is more affordable than UL or full IEC certification, which involve expensive third-party audits.
  • Faster Market Entry: CE certification is quicker, often taking weeks instead of months.
  • Simpler Process: CE allows self-declaration, reducing reliance on external labs.
  • Minimum Requirement: Since CE is mandatory in the EU, many companies view it as the lowest barrier to entry.

In other words, CE is often seen as the easiest, fastest, and cheapest way to access the European market. But relying on CE alone raises important safety concerns.

Is CE Alone Enough for BESS Safety?

The answer is no. While CE for BESS ensures legal entry into the EU market, it does not fully address the complex safety risks of modern energy storage systems.

BESS involves large-scale lithium-ion batteries, which can pose hazards like:

  • Thermal Runaway – Fire and explosion risk if cells fail.
  • High Voltage Risk – Danger of electric shock during installation or maintenance.
  • System-Level Failure – Risks from inverters, converters, or control systems.

To mitigate these risks, global safety standards go far beyond CE. Manufacturers often need UL, IEC, or national certifications depending on their target markets.

Key International Standards Beyond CE for BESS

Here are the most important certifications that complement CE for BESS:

1. IEC Standards (International)

2. UL Standards (North America)

3. National Certifications

Together, these standards ensure that a BESS is safe, grid-compatible, and globally marketable.

CE vs UL vs IEC: Key Differences

CertificationRegionScopeTesting RequirementMarket Perception
CEEuropeBasic health, safety, EMCSelf-declaration or notified bodyEntry-level compliance
UL 9540USA/CanadaFull system safetyThird-party lab requiredHigh credibility
IEC 62619 / 62933GlobalBattery + system safetyThird-party testingWidely respected
BIS / KC / PSENationalCountry-specific safety lawsMandatory local testsLegal requirement

This table shows why CE is the easiest to achieve but IEC and UL carry higher safety credibility.

Why BESS Needs Multiple Certifications

Unlike small electronics, BESS operates at industrial-scale energy levels, which makes multi-layer certification essential.

Why CE for BESS Matters
  • CE ensures compliance in Europe, but it does not evaluate system-level fire safety.
  • UL validates complete system safety and is trusted in North America.
  • IEC sets a global benchmark, especially for grid integration.
  • National standards guarantee local approval, allowing sales in markets like India, Japan, or Korea.

Therefore, CE should be seen as the foundation, while UL, IEC, and national approvals are the reinforcements. Together, they create a safe and credible BESS product.

Why Companies Should Go Beyond CE for BESS

Although CE is attractive for cost and speed, relying on it alone can lead to challenges:

  • Limited Market Reach: CE only works in Europe, not globally.
  • Lower Buyer Confidence: Utilities and large clients often demand UL or IEC reports.
  • Safety Risks: CE’s self-declaration model may overlook thermal runaway or fire propagation risks.
  • Regulatory Pressure: More countries are adopting stricter BESS safety laws.

Companies that invest in full certification portfolios gain stronger market access, brand reputation, and customer trust.

Conclusion: CE is Essential but Not the Final Step

CE for BESS is a mandatory starting point for European market access. It ensures compliance with basic safety, EMC, and environmental standards. However, CE is not enough to prove the full safety of complex battery energy storage systems.

Most companies choose CE because it is fast, affordable, and easy, but long-term success requires additional certifications like UL 9540, IEC 62619, and BIS. These provide independent validation, global acceptance, and higher safety assurance.

In the evolving energy landscape, BESS manufacturers and project developers must go beyond CE certification to build trust, reliability, and international growth opportunities.

❓ Frequently Asked Questions About CE for BESS

1. What is CE certification for BESS?

CE certification for Battery Energy Storage Systems (BESS) is a European conformity mark that shows the product meets essential EU safety, health, and environmental requirements. It’s a legal requirement for selling BESS in the European Economic Area (EEA).

2. Does CE certification cover fire safety in BESS?

No. CE certification ensures compliance with core directives but does not specifically address thermal runaway or fire safety risks. For complete system safety, manufacturers often pursue additional certifications like UL 9540A (fire safety) or IEC 62619 (battery cell safety).

3. How is CE different from UL or IEC certification?

CE Certification: Mandatory for the EU market, focuses on regulatory compliance.

UL Certification: Recognized mainly in North America, emphasizes product safety and fire prevention.

IEC Standards: Internationally accepted, providing detailed technical guidelines for testing and performance.

Using CE alone may open EU markets, but UL and IEC certifications build global trust and credibility.

4. Can I sell CE-certified BESS outside Europe?

Not necessarily. While CE certification allows access to EU markets, other regions like the US, Middle East, and Asia-Pacific often require local standards such as UL, BIS, or GB/T. Companies targeting global markets usually combine CE with additional certifications.

5. How long does CE for BESS take?

The timeline depends on the complexity of the BESS and the scope of testing. In general:

Large, complex systems: 3–6 months
Working with an accredited testing lab or certification body can speed up the process.

Simple systems: 4–8 weeks

6. Why is CE certification alone not enough for BESS safety?

Because BESS safety risks go beyond basic compliance. Issues like thermal runaway, grid stability, and fire containment need deeper testing. That’s why CE is often just the starting point, with UL, IEC, and country-specific certifications adding the necessary system-level validation.

Bess Certifications Guide
Rahul Jalthar

BESS Certifications Explained: What You Need to Know Before You Buy or Sell

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BESS Certifications: Battery Energy Storage Systems (BESS) are becoming a critical part of our renewable energy future. Whether you’re buying, selling, installing, or manufacturing BESS units, understanding the required certifications is crucial. Without proper certifications, your product may not be legally sold, safely operated, or even insured in many regions.

In this blog, we’ll break down the most important certifications for BESS and explain what they mean, why they matter, and how to ensure your system is compliant.

1. Why Are BESS Certifications Important?

Certifications are like a stamp of approval from trusted organizations. They prove that a BESS unit has passed safety, performance, and environmental tests. Without them:

  • You risk safety issues like fires or system failure.
  • Your product might be blocked from certain markets.
  • Insurance claims can be denied after accidents.
  • You might face legal problems or product recalls.

2. BESS Certifications Common Global Standards

Different countries and regions have different certification requirements. Here are some of the most common ones globally:

A. UL Standards (Mainly for North America)for BESS Certifications


UL (Underwriters Laboratories) is a leading safety organization in the U.S. These are some key UL standards for BESS:

Why it matters: UL certifications are essential for selling in the U.S. and Canada. Without these, your product won’t be accepted in most residential or commercial projects.

B. IEC Standards (International) for BESS


The International Electrotechnical Commission (IEC) sets safety and performance standards recognized worldwide.

  • IEC 62619 – Safety for Secondary Lithium Cells and Batteries
  • IEC 62933 – Series of standards for energy storage systems
  • IEC 62133 – Safety for portable sealed secondary cells
  • IEC 61427 – Performance of batteries used in renewable energy systems

Why it matters: Many countries outside North America refer to IEC standards for regulatory compliance, especially in Europe, Asia, and the Middle East.

C. CE Marking (Europe)


Products sold in the European Union must meet CE requirements. For BESS, this includes:

  • EMC (Electromagnetic Compatibility)
  • LVD (Low Voltage Directive)
  • RoHS (Restriction of Hazardous Substances)
  • Safety & Fire Protection

Why it matters: Without CE marking, you can’t legally sell your BESS product in the European Economic Area (EEA).

D. BIS (India)


In India, the Bureau of Indian Standards (BIS) regulates battery and BESS imports and production.

Why it matters: India is a growing BESS market, and local certifications are mandatory for government tenders and utility-scale projects.

E. CEC (Australia)


The Clean Energy Council (CEC) governs renewable energy products in Australia.

  • Products must be on the CEC approved list
  • Certifications must include both product testing and installer compliance

Why it matters: BESS products not listed with the CEC are ineligible for rebates or connection to the grid.

3. Certification for the Entire System, Not Just the Cell

One major mistake people make is assuming that a certified cell means the entire battery system is certified. That’s not true.

A complete BESS includes:

  • Battery cells or packs
  • Battery Management System (BMS)
  • Power Conversion System (PCS)
  • Cooling systems, enclosures, cables, and connectors

Each component AND the fully assembled system must meet certification standards.

4. Factory-Level Certifications

Besides product certifications, the factory that makes your BESS should also be certified:

  • ISO 9001 – Quality Management
  • ISO 14001 – Environmental Management
  • ISO 45001 – Occupational Health & Safety
  • IATF 16949 – (If automotive-related BESS)

Why it matters: Certified factories reduce the risk of defects, improve traceability, and meet import regulations more smoothly.

5. Who Issues These Certifications?

  • UL – Underwriters Laboratories (USA)
  • TÜV – Germany-based, issues CE and IEC certifications
  • Intertek – Testing and certification services globally
  • SGS – Certification body with international presence
  • CSA – Canadian Standards Association

Always work with internationally recognized certification bodies for credibility and global market acceptance.

6. Red Flags to Watch Out For

  • Only cell report is shown – This is not enough! Ask for system-level reports.
  • No thermal runaway test (UL 9540A) – Risk of fire is very high without this.
  • Non-recognized lab – Some factories use fake or local-only reports.
  • Outdated reports – Certification validity matters. Check the dates.
  • No factory audit certificates – Poor factory management = higher product risk.

7. Tips for Buyers & Project Developers

  • Always request full certification reports, not just summaries.
  • Ask for the name of the lab and the full system test, not just component tests.
  • Make sure the certification is valid for the target market (UL for USA, CE for Europe, etc.)
  • Work with verified sourcing or consulting agents who understand the compliance rules.

Conclusion


BESS certifications are not just paperwork—they’re your protection against risk, rejection, and regulatory trouble. Whether you’re importing, installing, or investing in energy storage systems, certification is your first line of defense.

Make sure your BESS is properly tested, certified, and factory-audited to avoid future headaches. If you’re not sure, work with local experts who can help verify everything before the deal is done.

Need Help?

If you’re buying BESS from China or anywhere else, and you want to make sure the product is safe and certified, I can help. I do:

  • Factory checks
  • Certification report verification
  • BESS system inspections
  • Compliance guidance for your target market

Let’s make your BESS project safer, faster, and fully compliant.