ESG reporting and BESS: Which data points can you actually extract?

When a company invests in a battery energy storage system, the question arises sooner or later: can the system deliver something that can be used in our ESG reporting? The answer is both yes and no, and the difference matters. A battery produces a continuous stream of operational data, and some of those figures are relevant for reporting. But raw operational data is not the same as a finished ESG metric, and a battery does not in itself determine what may appear in a sustainability report.

This article is a data-focused perspective, not legal advice. It explains which data points ESG reporting typically asks for, what an industrial BESS system can generically measure, where the difference lies between raw data and a reporting figure, and where the boundary sits relative to an auditor and a CSRD adviser. At the end there is a set of concrete questions that a company can take to its own ESG adviser.

What ESG reporting typically asks for

Most frameworks for sustainability reporting care about some of the same basic quantities on energy. Four recur.

Energy consumption: How much energy the company uses. Under the European reporting standards, a company must, where relevant, disclose its total energy consumption and its energy mix, stated in megawatt-hours. That is a volume measure describing how much is consumed and how consumption is distributed.

Share of renewable energy: As part of the energy mix, how large a share of consumption comes from renewable sources. That is a composition measure that says something about the profile of the energy consumption the company has already accounted for.

Flexibility: The ability to shift consumption and production in time has become a relevant property in an energy system with a lot of solar and wind. Battery storage typically delivers short-term flexibility over hours and can reduce losses and congestion in the electricity grid. That is a qualitative property that can be described, but that is not in itself an emissions inventory.

Resilience: Finally, part of reporting concerns resilience. The European standards cover not only reduction of climate impact, but also climate adaptation and the company's ability to adapt its operations. Here, a system that supports a stable electricity supply can feature as one element, again as a qualitative description.

Common to the four is that they concern consumption, composition and properties. None of them require knowing a battery's internal figures, but a battery can contribute data that describe part of the picture.

What a battery actually measures

An industrial BESS system is thoroughly instrumented. To be controlled and monitored, it continuously records a series of standard data points, and these are generic across manufacturers. The most important ones are easy to grasp.

• Energy throughput: How many kilowatt-hours are charged into the battery, and how many are discharged again. That is the most directly measured quantity and is stated as time series of energy in and energy out.
• Charge and discharge cycles: A running count of how many times the battery has been charged and discharged. The number of cycles is one of the standard results a battery accounts for, and it relates to how hard the system works.
• State of Charge: The battery's state of charge, meaning what share of usable capacity is available at a given time, stated as a percentage.
• Efficiency: Because there are losses in charging and discharging, the energy that comes out is less than what was charged in. Round-trip efficiency is stated as discharged energy divided by charged energy over a period.
• Availability and uptime: What share of the time the system is ready for operation. This is an important data point, but also one that requires more than a single meter to establish, which we return to.
• Overall market activity: When the system has been active in the market, meaning an overall picture of when it has charged and discharged relative to prices and need.

These are data that describe how the battery runs. They are precise and measurable, and they are useful. But they describe the system, not the company's overall climate accounts.

From raw data to reporting figures

Here lies the most important point in the whole topic. An operational data point is not automatically an ESG metric. The jump from one to the other requires a methodological choice, and that choice belongs with whoever prepares the reporting.

A concrete example is availability. One might think that uptime can be read directly from when the battery has had throughput. But availability cannot be established from meter data alone, because there are hours when a fully functional system stands idle, simply because it has not been called on. To distinguish between "out of operation" and "in operation, but not active," one must know the dispatch commands and the system's response, not just the energy figures. A figure that looks simple turns out to require interpretation.

The same applies to the relationship between the battery's figures and a Scope 2 inventory. A Scope 2 inventory is based on the company's measured electricity consumption in kilowatt-hours or megawatt-hours and can be made with a location-based method that uses the grid average, or a market-based method that uses contractual instruments such as guarantees of origin. The battery's energy throughput is not the same as the company's consumption, and neither of the two Scope 2 methods is in itself a calculation of how much a battery has displaced. The data points can serve as input, but they do not replace the method.

Finally there is the climate effect. A claim that a battery has displaced CO₂ requires a documented method that compares the system's actual operation with a counterfactual situation. That is an exercise that builds on more than operational data, and we cover it in more detail in our article on CO₂ displacement. The point here is simply that none of the data points a battery measures in itself constitutes an emissions figure.

Where the consumption figures come from

A practical point that is often overlooked is that the consumption figures a Scope 2 inventory rests on do not come from the battery, but from the electricity meter. In Denmark, a company can access its own consumption data, including hourly consumption and meter data, via Energinet's DataHub. Energinet is Denmark's national transmission system operator, and DataHub is the central platform for electricity meter data. That is the source that describes how much the company has actually drawn from the grid.

That means reporting typically draws on several data sources at once: consumption data from the meter, any contractual instruments from the electricity agreement, and operational data from systems such as a battery. Keeping those sources separate is part of being able to stand behind the figures. The battery's data describe the system's operation, the meter's data describe consumption, and it is the adviser's task to put them together in a way that fits the chosen method.

The boundary with the auditor and CSRD

That leads to the boundary that must always stand clearly. A battery is a data source, not a reporting function, and a data provider is not an auditor.

For companies covered by the EU rules on sustainability reporting, sustainability disclosures are not just something one writes. They are subject to an assurance requirement and must be published together with an assurance statement, which from the first year of application is based on a so-called limited assurance engagement. That engagement is the responsibility of an auditor or an independent assurance provider, not of whoever has supplied a piece of equipment. Where a battery belongs in the reporting itself, and which requirements apply, is a matter for a proper CSRD context, which we describe separately in the article on CSRD and ESRS.

There is also an accountability relationship. A company that wants to market itself with green statements must itself be able to document them under the Danish Marketing Practices Act's rules on misleading claims. The Danish Consumer Ombudsman (Forbrugerombudsmanden) is the authority that oversees these rules. A data provider can supply the figures behind the system's operation, but cannot take over responsibility for a claim of which it is not the sender. That is therefore not a technical detail, but a real division of labour: we deliver operational data, and the customer and the customer's own adviser or auditor own the reporting and any external statement.

ZynexGroup's approach to system assessment

Our role is bounded, and it should be described as such. We develop, deliver and optimise industrial BESS systems and make operational data available. We are not ESG advisers or CSRD consultants, and we do not prepare sustainability reports for the customer.

Concretely, our platform can make generic operational data available so the customer can use them in their own documentation. That concerns energy consumption and energy throughput in kilowatt-hours, charge and discharge cycles, State of Charge, availability and uptime, as well as an overall picture of market activity and flexibility. These are operational and monitoring data that the customer and the customer's own advisers can take as a starting point. Qualitatively, a system can also support the electricity grid and better utilisation of renewable energy, but that does not in itself make a company CO₂-neutral.

By contrast, we do not deliver a concrete CO₂ displacement tool that turns operational data into an emissions figure by comparing consumption and dispatch with a counterfactual grid mix. Such a tool is not available from us today, and we do not put forward a figure that we cannot stand behind methodologically. If a company wants to account for a displacement, that exercise belongs with the customer's own climate or ESG adviser, possibly with operational data from the system as input.

We offer a 6-year payback guarantee on BESS systems. It concerns the economics and says nothing about a reporting figure or a climate effect, and those questions should be kept separate.

Questions for your own ESG adviser

Because the methodological choice belongs with the adviser and the auditor, the most useful preparation is to ask the right questions. The following is not legal advice, but a practical way to clarify what operational data from a system can and cannot be used for in your specific reporting.

• Which framework do we report under? Is it ESRS under CSRD, a voluntary standard or a customer requirement, and which energy data points does it specifically require?
• Which data points are relevant for us? Do we need total energy consumption, share of renewable energy, or also qualitative descriptions of flexibility and resilience?
• Where does each figure come from? What is taken from the electricity meter and DataHub, what from the electricity agreement, and what, if anything, from a system's operational data?
• Which Scope 2 method do we use? Location-based, market-based or both, and what does that mean for how a system's data are incorporated?
• What requires assurance? Which figures must be auditable, and what documentation does the auditor require to be able to issue an assurance statement?
• What can we say externally? Which formulations can we stand behind, and which require a method or documentation that we do not have today?

The answers determine whether a system's operational data are relevant for your reporting, and in what form. They also ensure that the boundary between operations and reporting is drawn before the figures are used.

Overall perspective

An industrial BESS system can deliver well-defined operational data: energy throughput in kilowatt-hours, charge and discharge cycles, state of charge, efficiency, availability and an overall picture of market activity. Those data are real and measurable, and they can enter as input in a company's own reporting.

But they are precisely input, not a finished ESG inventory. A reporting figure requires a methodological choice, the consumption figures come from the meter and not from the battery, and a climate effect requires a documented method that cannot be read from operational data alone. For companies covered by CSRD, the reporting must also be assured by an auditor. The honest position is therefore to keep what can be measured in operations separate from the reporting figures and claims that require an independent method and an external specialist assessment. The same distinction between operations, reporting and communication underlies our whole approach to pragmatic sustainability with BESS, and it is closely linked to how finance and ESG should look at Scope 2 and flexibility.

Assessing the potential for your facility

If you want to clarify what a battery can realistically contribute at your site, and which operational data a system can then make available for your own reporting, we are happy to have a data-based conversation. We start from your own data: grid connection, consumption profile and history. On that basis we make an initial assessment of whether there is a match, and we are clear that the reporting itself and any external claim belong with you and your own adviser, not with us. You are welcome to contact us.