Connecting a type B battery storage system to the grid
Connecting a type B battery storage system (1–9.99 MW) involves three parties and several deadlines. We handle the technical whole and make sure every requirement is covered, so the battery starts earning for its owner as quickly as possible.
Division of work in our projects
Components and automation equipment
Components and automation equipment for power distribution and transmission are designed and ordered through Elpartner:
- Transformers and transformer substations: MV step-up transformers and main transformers
- Switchgear
- Automation equipment
Control and SJV requirements
Power plant controllers and everything related to control and SJV requirements through our sister company Greencontrol.
- Fingrid
- Connectee
- Network operator and connectee
- Elpartner or Greencontrol involved
Study and design
Requirements are clear before anything is ordered.
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Step 1: Network operator requirements (“stage 0”)
Network operator and connecteeThe requirements of the network operator at the connection point are clarified: protection and its principles, KVT controls, reactive power capacity, control mode and control point, and the scope and implementation of real-time data exchange. The type B questionnaire in Fingrid’s VJV/SJV2024 start tool helps go through these with the network operator.
Elpartner: Equipment-related items: transformers and switchgear.
Greencontrol: Items related to control mode, control point, reactive power capacity, protection, data exchange and other SJV requirements. -
Step 2: Connectivity study
Network operator and connecteeContacting the network operator at the connection point: connectivity and technical requirements.
Note: There must be free capacity in the area for the storage system to be connected.
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Step 3: Equipment design
ConnecteeThe substation, protection, automation and control are designed to meet the requirements.
Elpartner: Design of transformers, transformer substations and switchgear.Greencontrol: Control solution and power plant controller (GC-PPC) in line with the SJV requirements, plus protection, RTU and communications.
Capacity and agreements
Capacity is secured and the agreement is signed.
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Step 4: Capacity reservation from Fingrid
FingridFingrid’s connection agreement enquiry practice for energy storage: capacity is reserved and confirmed with Fingrid.
Note: The reservation is valid for a limited time, and some areas have temporary connection restrictions for energy storage.
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Step 5: Connection agreement
Network operator and connecteeConnection agreement with the network operator at the connection point.
Procurement and connection permit
Equipment is ordered and technical data is submitted.
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Step 6: Equipment order
ConnecteeEquipment is ordered according to the design.
Elpartner: Transformers, transformer substations, switchgear and automation equipment, compatible with each other.Greencontrol: Power plant controller (GC-PPC). -
Step 7: Technical data to Oma Fingrid
ConnecteeThe data in SJV table 7.1 is submitted to Oma Fingrid. The network operator at the connection point opens the project.
Elpartner: Technical data and documents for the equipment.Greencontrol: Data related to control and SJV requirements. -
Step 8: Connection permit
Network operator and connecteeThe network operator grants permission to transfer power at the connection point.
Commissioning and reserves
The plant is tested and the battery starts earning.
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Step 9: Real-time data exchange with Fingrid
ConnecteeReal-time data exchange is taken into use to the extent required by the grid code and Fingrid’s main grid service terms.
Note: Fingrid must be contacted about 2 months before production starts.
Greencontrol: RTU, communications and signal tests. -
Step 10: SJV commissioning tests
ConnecteeThe connectee performs and checks the commissioning tests in chapter 15 of SJV2024.
Greencontrol: Test programme, commissioning tests and reporting. -
Step 11: Network operator statement
Network operator and connecteeThe network operator gives a written statement on the project status: the equipment meets the connection and network service terms, the key grid code requirements are met, the plant has permission to transfer power, the SJV table 7.1 material is in Oma Fingrid, real-time data exchange is in use and any deficiencies are listed.
Note: The statement is a prerequisite for reserve markets before the final operational notification.
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Step 12: Reserve tests and market integration
ConnecteeReserve regulation tests can start once the statement has been given and the commissioning tests are done.
Greencontrol: Regulation tests and integration with the aggregator’s system, for example NSC EnergyOpti or Elisa Griddle. -
Step 13: Reserve market operation can start
The battery earns for its owner.
Note: Without the final operational notification (FON), reserves can be provided for up to 12 months from the start of power feed-in.
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Step 14: Final operational notification (FON)
Network operator and connecteeThe network operator issues the final operational notification once the deficiencies listed in the statement have been corrected.
Remember changes too: if an existing plant is modified, for example its controller is replaced or reparameterised, Fingrid must be asked to assess the impact of the change.
Based on Fingrid’s example of the type B energy storage connection process and Fingrid’s guidance on prerequisites for reserve market participation (5 October 2026). This description is meant to give an overview. The exact and current requirements are always in the official requirements of Fingrid and the network operator at the connection point (YLE, VJV, SJV, KJV). Updated 10/2026.
Fingrid materials: VJV/SJV2024 start tool (xlsx) and Prerequisites for reserve market participation (pdf, in Finnish).
Planning a battery storage project?
Tell us the site size, connection point and schedule. We will tell you which steps lie ahead for your project and how to reach production fastest.