EU Battery Rules: What ESS Developers Must Do Now

Most utility-scale storage projects signed in 2025 will still be running in the 2040s. Whether those assets earn or burn value now depends a lot on three letters: CE.

Since 18 August 2024, the EU Batteries Regulation has turned CE marking from a formality into a gatekeeper for almost every serious energy storage system (ESS) targeting the European market. For green technology developers, investors, and OEMs, this is no longer a niche compliance topic; it’s a core part of project bankability and long-term asset value.

This matters because the EU Battery Regulation doesn’t just ask "Is this product safe today?" It asks:

• How was this battery produced?
• Can we trace its materials and carbon footprint?
• What happens when it’s repurposed or recycled?

For a sector betting on batteries to enable clean energy, smart grids, and low-carbon industry, that’s a big shift—but also a huge opportunity.

In this article, I’ll unpack what the first year of the EU Battery Regulation has meant for energy storage, why CE marking is biting harder for ESS than for other batteries, and how smart operators are turning regulatory pain into a competitive advantage.

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1. EU Batteries Regulation: What’s Actually Changed for ESS?

The EU Batteries Regulation is now the central legal framework for batteries in Europe. For stationary energy storage systems, it combines safety, sustainability, and digital transparency in one package.

The key change: no CE mark, no market access. Since August 2024, batteries placed on the EU market must carry a CE marking that confirms compliance with the relevant parts of the regulation.

For ESS, that means dealing with:

• Industrial battery rules (ESS are treated as a subcategory of industrial batteries)
• Stationary storage safety rules
• Information and transparency rules (state-of-charge, lifetime, traceability)
• Future carbon footprint and due diligence obligations

The regulation is built around four main pillars:

1. CE marking & conformity assessment
2. Battery Passport (digital identity and data platform)
3. Due diligence obligations across the supply chain
4. Waste battery management & extended producer responsibility

Right now, CE marking is the first pressure point. But by 2027, Battery Passports and due diligence will be just as critical for green technology companies trying to sell, finance, or operate ESS in Europe.

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2. Why ESS Compliance Is Harder Than You Think

Here’s the thing about stationary energy storage: on paper, it’s “just” another battery category. In practice, it’s a lot more complex than putting a CE mark on a single lithium-ion pack.

ESS present a tougher compliance challenge because they combine:

• High energy and power density (multi-MWh systems)
• Long lifetimes (10–20+ years)
• Integration complexity (inverters, EMS, BMS, fire systems, building interfaces)
• Diverse use cases (grid services, C&I storage, residential, microgrids, second-life)
• Installation context (inside buildings, next to critical infrastructure, urban areas)

The first year of the regulation has exposed several recurring pain points for ESS players:

• Teams unaware or underestimating the new requirements
• Confusion over legal roles: manufacturer vs. producer vs. importer vs. distributor
• Different interpretations by national authorities across EU member states
• Overlaps with other EU laws (REACH, WEEE, worker safety, medical rules in some sites)
• Ambiguous terms like “placing on the market” causing delays in project sign-off

What I’ve seen work best is this: companies that treat compliance as a design constraint from day one, rather than a last-minute checkbox, are the ones still hitting schedules and getting financed.

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3. CE Marking for Energy Storage: A Practical Roadmap

For anyone building or specifying ESS for the EU, CE marking is the first hurdle to clear—and it’s more than just a label.

Quick CE compliance checklist for ESS

Use this as a sanity check before you start serious project development or procurement:

1. Define your role
   Are you the manufacturer (CE-responsible), producer, importer, or distributor? For project-based ESS, this can be tricky—EPCs and integrators often end up with more responsibility than they realise.

2. Confirm the battery category
   ESS are treated as industrial batteries, usually >2 kWh. That means they’re subject to Articles 6, 7, 8, 10, and 13, plus ESS-specific Articles 12 and 14.

3. Check which articles are already binding
   As of late 2025, the core ones in force for industrial/ESS batteries include:

   • Article 6: Sustainability and safety requirements
   • Article 9 & 10: Performance and durability / labelling
   • Article 13 & 14: Information, SoC, and expected lifetime
   • Article 12: Safety of stationary storage batteries

   Articles 7 and 8 (on carbon footprint and recycled content) are being phased in by category.

4. Build your technical documentation package
   This typically includes:

   • Risk analysis and risk mitigation measures
   • Safety and performance test reports
   • Design documentation and schematics
   • Instructions, labels, and safety information
   • For second-life batteries: functional test data and health checks

5. Issue the Declaration of Conformity
   The manufacturer (or CE-responsible party) signs a formal document stating the product complies with the relevant parts of the regulation.

6. Apply the CE mark
   Once the process is complete, the CE mark goes on the battery (and often on system documentation).

Why notified bodies matter (especially for Article 7)

The next big wave is Article 7 – carbon footprint rules. For each affected category, once Article 7 takes effect, manufacturers get about one year to:

• Calculate product-level carbon footprints
• Classify batteries into performance classes
• Have their data and processes checked by a notified body (third-party conformity assessment body)

For ESS, the stress point isn’t just the math—it’s the data requirements:

• Life-cycle modelling, including raw materials and manufacturing
• Energy mix at production sites
• Supply chain data from multiple tiers
• Rules for recalculating when the design or process changes

With limited notified body capacity, waiting until Article 7 fully applies to your category is a risky bet. The smarter move is to engage early, test your data flows, and treat carbon accounting as part of your product architecture.

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4. ESS-Specific Requirements: Safety, SoC, and Second-Life

Stationary ESS don’t only have to comply as “industrial batteries.” They also trigger additional articles because of where and how they operate.

Article 12 – Safety of stationary storage batteries

Article 12 demands evidence of safety testing using state-of-the-art methods, typically referencing standards in Annex V and relevant IEC/EN standards.

For green technology projects, that usually translates into:

• System-level abuse tests (thermal, electrical, mechanical)
• Fault simulations and protection validation
• Fire behaviour, venting, and containment strategies
• Evaluation of installation conditions (room, container, outdoors)

One recurring issue: system vs. subsystem testing. A pack that passed tests on its own can behave differently once wired into a full system with higher voltages and new failure modes. Many failures in testing stem from:

• Protection devices not rated for final system voltage
• Wiring configurations that introduce new short-circuit paths
• Control dependencies (e.g., EMS–BMS handshake) not considered originally

Good practice is to plan both pack-level and system-level testing from the start and align test plans with your notified body or test lab before hardware is frozen.

Article 14 – Information on SoC and expected lifetime

ESS must provide clear information on:

• State of charge (SoC)
• Expected lifetime
• A software reset option when batteries are repurposed

On the surface, this sounds like a labelling exercise. In reality, it forces you to:

• Define realistic lifetime metrics under specific duty cycles
• Align commercial warranties with technical reality
• Implement SoC and State of Health (SoH) monitoring that’s robust and transparent

For operators and financiers, this is actually a win. Standardised lifetime and SoC reporting reduces guesswork in asset valuation, especially in long-term green energy portfolios.

Second-life batteries: where it gets really interesting

Second-life ESS are central to the green technology story: extending battery life reduces resource use and emissions. The EU regulation supports this—but it also raises the bar.

For second-life batteries in ESS, you’re looking at:

• Functional and comprehensive health checks before reuse
• Full traceability of origin and prior use
• Digital Battery Passport integration
• Extended Producer Responsibility (you don’t escape obligations just because it’s “used”)
• A particularly demanding risk analysis, since:
  • Original design documentation is often missing
  • Historical usage and environment are only partially known
  • Safety margins may be lower than for new batteries

The takeaway: second-life ESS can absolutely be a viable green technology and business model, but the bar for testing, documentation, and risk management is higher than many start-ups expect.

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5. Beyond CE: Battery Passport, Due Diligence, and New Business Models

While CE conformity is front and centre right now, the next two–three years will bring the other pillars of the EU Battery Regulation into full force. These are where digitalisation and AI start to intersect powerfully with green technology.

Battery Passport (from 2027)

The Battery Passport is a digital identity for each eligible battery. For ESS, it will store both static and dynamic data, such as:

• Technical specifications and configuration
• Manufacturing details and materials
• Carbon footprint data
• Real-world performance, usage, and degradation

For operators and OEMs, this unlocks:

• Standardised datasets for predictive maintenance
• Better lifetime extension through optimised operating strategies
• Higher residual value for repurposed or second-life assets

I’m convinced this will change how ESS are financed. Assets with reliable, passport-backed data will be easier to underwrite, bundle, and trade.

Due diligence obligations (from 2027)

Larger operators will also face due diligence requirements around:

• Human rights and labour conditions in the supply chain
• Environmental risks and impacts
• Public reporting and third-party verification

For serious green technology players, this isn’t just compliance theatre—it’s part of proving that their climate solutions aren’t built on social or environmental harm upstream.

Waste batteries and Extended Producer Responsibility (from 2025)

From August 2025, waste battery rules and Extended Producer Responsibility (EPR) kick in more fully:

• Producers must organise collection and recycling
• Hazardous materials must be handled safely
• Recovery and recycling targets apply over time

For ESS developers, this means you should design end-of-life logistics into your business model now: reverse logistics, recycling partnerships, and clear ownership of EPR obligations.

Where AI and data turn compliance into value

Here’s where this connects back to the wider green technology and AI narrative:

• Battery Passport and CE data give you high-quality, standardised inputs
• AI and advanced analytics turn that into actionable insights: health scoring, dispatch optimisation, degradation-aware trading, end-of-life routing

Examples that are already emerging:

• Health-index scoring for ESS fleets to prioritise maintenance and redeployment
• Warranty optimisation based on real usage patterns, not generic assumptions
• Automated end-of-life decision support (reuse vs. repurpose vs. recycle)

Companies that treat regulatory data as a strategic asset rather than a burden will win on both cost and sustainability.

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6. What ESS Developers and Investors Should Do Next

The reality? Complying with the EU Battery Regulation for ESS is demanding—but manageable if you start early and structure it properly.

Here’s a practical action list for the next 6–18 months:

1. Map your role and responsibilities
   Clarify who is legally the manufacturer / producer / importer in each project.

2. Run a gap analysis on CE requirements
   Compare your current documentation, test coverage, and risk analysis with Articles 6, 10, 12, 13, and 14.

3. Plan system-level testing upfront
   Don’t rely solely on cell or pack certificates. Align test plans with Annex V methods and relevant ESS standards.

4. Engage with a notified body or testing partner early
   Especially if you know Article 7 (carbon footprint) will soon apply to your category.

5. Develop a data strategy for Battery Passport
   Treat operational data as a core feature: structure it, standardise it, and plan how AI will use it.

6. Design for end-of-life and second-life
   Decide whether you want to own repurposing and recycling, or partner. Either way, build it into contracts and cash-flow models.

For companies in the green technology space, this regulation is more than a legal hurdle. It’s a forcing function that aligns safety, sustainability, and digital transparency across the entire battery lifecycle.

Those who adapt early will not only pass audits; they’ll build more bankable projects, longer-lived assets, and more credible climate impact.

The next question isn’t whether ESS can comply with the EU Batteries Regulation. It’s which players will use it as a platform to build smarter, cleaner, and more valuable energy storage businesses.