Battery energy storage systems are increasingly considered a standard element of modern energy projects.
In many cases, the assumption is straightforward: adding a battery will improve the system — technically, economically, or both.
In practice, this assumption does not always hold.
Whether a BESS creates value depends less on the technology itself and more on the role it plays within a specific system.
A question of role, not technology
One of the most common issues is the absence of a clearly defined use case.
A battery can serve very different purposes — from peak shaving to energy shifting or participation in ancillary services. These applications follow different operational logics and are not easily combined.
If the intended function is not clearly defined, the system often ends up trying to do several things at once, without performing any of them particularly well. In such situations, the battery introduces additional complexity rather than improving overall performance.
Sizing presents a similar challenge. In early concepts, battery capacity is often derived from general assumptions rather than from actual system requirements. This can lead to oversized systems that are only partially utilised in operation.
More capacity does not necessarily translate into more value — especially if the underlying flexibility is limited.
Constraints define performance
The role of the grid is another factor that is frequently underestimated.
In theory, a BESS can access multiple revenue streams. In practice, grid constraints and regulatory conditions define which of these options are actually available. Limited connection capacity or restrictions on feed-in can significantly reduce the operational potential of a battery.
This is closely linked to the way revenue assumptions are made.
Many models rely on combining different value streams, assuming stable market access and predictable price signals. In reality, these conditions are neither constant nor independent of each other.
A business case that depends on optimising across several uncertain variables becomes inherently sensitive — and often less robust than it appears.
Integration determines value
A battery does not operate in isolation. Its performance depends on how it is embedded within the broader system — how it interacts with generation, consumption and external constraints.
Without a clear operational strategy, even a technically well-designed BESS remains underutilised.
Conclusion
A BESS can be a valuable component of an energy system. But it is not inherently beneficial. Its value emerges only when there is a clear role, a suitable system context and a well-defined operational logic.
In some cases, the most effective decision is not to add a battery — but to recognise that the system does not require one.
