Delayed BESS control decisions can raise project capex

Control architecture decisions are often treated as a purely technical matter and deferred until late in battery energy storage projects, but doing so can have significant commercial and contractual consequences, according to Kiwa PI Berlin.

In the first part of a new series on lessons learned from BESS contract negotiations, Beñat Murua, senior project manager at Kiwa PI Berlin, said early decisions on control architecture influence hardware sizing, the allocation of responsibilities between contractors, integration costs and plant acceptance criteria.

Kiwa said multiple control configurations are possible, each carrying different implications for cost, complexity and risk allocation. These include the use of a single power plant controller (PPC) for an entire facility or a dedicated PPC for the battery system operating under a higher-level plant controller, an approach commonly used in hybrid projects. A remote-control unit may also be required to manage communications with transmission system operators (TSOs) or distribution system operators (DSOs).

The appropriate configuration depends on the type of project, whether it is a standalone BESS installation, a new hybrid plant or the addition of storage to an existing solar facility.

The company also highlighted the importance of defining, at an early stage, communication responsibilities with TSOs and DSOs, the protocols to be used and the logic governing dispatch instructions sent to power conversion systems (PCS).

Operational optimization strategies should also be established from the outset, as they determine how systems such as the energy management system (EMS), PPC and supervisory control and data acquisition (SCADA) platform interact and divide responsibilities.

According to Kiwa, failing to define the control architecture early can lead to overlap between EPC contractors and equipment suppliers, particularly when both include similar control solutions within their scope of work. The resulting duplication can increase project CAPEX by around 3%, with a complete PPC and SCADA package typically costing between €300,000 and €600,000 depending on its functionality.

The company said postponing decisions on systems such as EMS until contract negotiations can also result in technical incompatibilities that lead to delays and additional costs.

Kiwa concluded that control architecture should be regarded as a strategic decision to be addressed during the early stages of project development. While there is no universal solution suitable for every BESS project, identifying the most appropriate configuration early can help optimize costs, reduce integration risks and support timely delivery in an increasingly demanding technical and regulatory environment.

From pv magazine España