This article is the second part of a three-part blog series titled Battery Energy Storage Systems in Electricity Markets. In the first article, we explored the role of battery energy storage systems (BESS) in electricity markets. In this second part, we focus on what happens after the technical solution has been selected – in other words, how a battery energy storage system is prepared for participation in reserve markets.
Participation in reserve markets starts with planning
Implementing the technical solution is only the first step on the journey to electricity markets. Equally important is understanding what participation in reserve markets requires in practice. While the early stages of a project typically focus on equipment selection and control systems, preparing a BESS for market participation requires careful planning, interpretation of technical requirements and close cooperation between all stakeholders.
Fingrid emphasises the importance of early project planning in its guidance – and for good reason. From the outset, it is essential to assess which reserve products the asset is suitable for and what technical requirements each product imposes. In Finland, reserve markets include FFR, FCR-D, FCR-N, aFRR and mFRR, each with its own requirements for response time, control accuracy and availability. Not every battery system is capable of participating in every reserve product without further system optimisation.
The decisions made during this stage have a significant impact on the rest of the project. For example, some battery systems can provide frequency-controlled response independently (typically a C/D-type solution), while others require an external controller before they respond at all (generally referred to as B-type systems). Between these are solutions that meet some, but not all, market requirements. Understanding these differences during the planning phase helps avoid costly surprises later in the project.
Market access is more than a technical challenge
Technical performance alone is not enough. Communication systems and regulatory requirements must also be considered. For example, NC ER requirements do not apply to B-type facilities, which may simplify implementation. Nevertheless, reliable real-time data exchange remains a fundamental requirement for participation in reserve markets. The system must be able to communicate reliably with both Fingrid and other market participants.
Once the technical implementation and market suitability have been evaluated, the project moves on to prequalification testing. This is where it becomes clear whether the system actually performs in accordance with the required specifications. The reserve provider is responsible for conducting the tests, while Fingrid reserves the right to monitor them. These tests are far more than a formality — they are a critical step in validating the system's performance under practical operating conditions.
Syncron Tech has supported customers in numerous prequalification testing projects. Our role is typically to ensure that all system functionalities — from control logic to communication interfaces — meet Fingrid's technical requirements. We also assist with the preparation of project documentation, which often proves to be a much larger task than initially expected. In practice, documentation and the integration of multiple systems frequently become the most time-consuming aspects of a project unless they are addressed early and supported by the right expertise.
Successful market participation depends on the whole system
It is equally important to understand how responsibilities are divided between the different parties involved. Although technical implementation and testing are often carried out together with specialist partners, the customer remains responsible for several key market participant obligations. These include signing reserve market agreements and defining the real-time data exchange and market messaging required as part of the Balance Responsible Party (BRP) framework. Only after these steps have been completed can the asset participate in reserve markets.
Looking ahead, the role of the aFRR market is expected to continue growing. This will place increasing demands on system control and integration, as aFRR requires continuous and highly accurate automatic control. The ability of a battery energy storage system to participate in this market cannot be taken for granted — it requires the right system architecture and a well-designed control solution.
Successful market entry ultimately depends on managing the project as a whole. The technical system, control, communications, testing and market processes form a chain in which every link must function reliably. When each element is carefully designed and implemented, a battery energy storage system becomes far more than a technical investment—it becomes an active participant in electricity markets.
Fingrid has outlined the main stages of participation in the reserve markets in its process description. The process progresses through the Prerequisites, Prequalification Tests, System Work and Market Agreements, and Start of Bidding phases. Further information is available on Fingrid's website: How to participate in the reserve markets.
In the third and final article of this blog series, we move from theory to practice. We will explore what prequalification testing for different reserve products actually involves, the technical requirements that must be met, and the practical lessons learned from real-world projects.
If you are interested in this topic and would like to discuss it further, feel free to contact us lasse.kankainen@syncrontech.com
