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.
This article is the first part of a three-part blog series titled Battery Energy Storage Systems in Electricity Markets. The series explores how battery energy storage systems (BESS) operate in electricity markets, how they are integrated into reserve markets, and practical experiences from testing different ancillary services. In this first part, we focus on BESS from the perspective of electricity markets. Battery energy storage systems from an electricity market perspective Battery energy storage systems have become a key element in the ongoing transformation of electricity markets. Flexibility has become one of the most important characteristics of modern power systems. However, in practice, flexibility is not achieved through battery capacity alone. The critical factor is how the entire system is designed, controlled, and integrated into both the power system and electricity markets. This is where differences between BESS solutions become evident. At Syncron Tech, we have been involved in several battery energy storage projects in recent years. Based on our experience, the technical implementation plays a decisive role in project success. A common assumption is that a battery system can be directly connected to Fingrid’s reserve markets. In practice, the situation is more complex. There are significant differences between battery technologies and system implementations, for example in response times, control accuracy, and controllability. These characteristics ultimately determine whether the system meets market requirements and passes the required compliance testing. These challenges typically become visible during the grid compliance assessment process. This is not about a single requirement, but a combination of several aspects, including frequency and voltage support, measurement systems, protection schemes, and real-time communication. In many projects, it becomes clear at this stage that inverter-level control alone may not be sufficient. PPC as the bridge to electricity markets At this point, the control system becomes essential, particularly the Power Plant Controller (PPC). Centralized plant-level control enables the entire facility to be operated as a single coordinated system, implementing the control logic required by Fingrid and adapting to the requirements of different reserve markets. It also enables reactive power capability at the point of connection and supports required market communication interfaces. In practice, the PPC acts as a bridge between the technical system and electricity markets. The overall solution matters Recently, attention has also been drawn to the practical operation of battery systems. Reserve markets require fast power changes, which means continuous switching between charging and discharging and steep ramp rates. However, overly aggressive control strategies can accelerate battery degradation, reduce performance, and in the worst case impact warranty conditions. Therefore, a balance must be found between market optimization and technical lifetime performance. In many projects, a workable approach has been to keep the core BESS delivery relatively lean, while complementing the overall system with a dedicated PPC solution. This provides the necessary flexibility without overengineering the entire installation. At the same time, it improves interoperability between different stakeholders, such as traders, control centers, and grid operators. It is also important to note that grid code requirements are extensive, and it is not always practical to implement everything in-house. Competent partners therefore play a key role throughout different phases of the project. When system architecture, control strategy, and market requirements are considered as a whole, a battery energy storage system becomes more than just a physical asset — it becomes an active and value-generating part of the power system.
Did you know that starting January 1, 2026, an amendment to the Electricity Market Act will enable flexible electricity connections? The power system is undergoing rapid transformation. Industrial electrification, renewable energy generation, energy storage and new high-demand loads are driving a rapid increase in connection capacity requirements, while in many areas the grid is already operating near its limits. Flexible electricity connections provide a solution in situations where full connection capacity is not immediately available. They enable investments and operations to commence without long waiting periods for grid reinforcement. In practice, however, a flexible connection always requires a reliable power management system.
