On 9 October 2026, Fingrid Oyj, the Finnish transmission system operator, introduced new specific study requirements (Fi: erityistarkasteluvaatimukset) for solar and wind power plants connecting to converter-dominated areas of the Finnish electricity system. In practice, wind and solar power plants connecting to converter-dominated areas will now be required to demonstrate grid-forming capability to ensure that the connection of the power plant does not endanger the stable and secure operations of the grid. Converter-dominated areas are areas in which wind and solar power generation is concentrated with relatively few nearby synchronous machines, such as is the case in Western Finland. The new grid-forming requirements do not apply to existing power plants or to power plants under construction that already have a connection agreement.
The requirements are issued under the specific study framework of Fingrid’s grid code for power plants (VJV2024, chapter 5) and apply to new connection agreements signed after 9 October 2026. This will be an absolute precondition for satisfying Fingrid’s system technical requirements and, consequently, for connecting a converter-connected power plant to the grid. The requirements apply to all converter-connected power plants that have an Equivalent Short Circuit Ratio (ESCR) value of 1.0 or lower at the connection point. Fingrid provides the ESCR value to connecting parties, upon request, as part of the specific study evaluation.
Ways to meet the grid-forming requirement
The grid-forming capability can be delivered either through the power plant’s own control system or through supplementary equipment. The supplementary equipment may take the form of i) a grid-forming battery energy storage system (BESS), ii) an energy-storage-equipped STATCOM (ES-STATCOM), or iii) a synchronous machine such as a synchronous condenser. Where the grid-forming function is delivered through separate supplementary equipment rather than the power plant’s own converter units, the equipment must be located as close as possible to the power plant’s converter units. The supplementary equipment may be connected either:
- as part of the power plant’s internal electrical system;
- to the same substation of the network operator or Fingrid to which the power plant is connected by a radial link; or
- to the same 110 kV power line of the network operator or Fingrid to which the power plant is connected.
The electrical distance between the power plant and the supplementary equipment may not exceed 60 kilometres.
The specific study requirements set out the technical requirements for the supplementary technology. The minimum sizing of the supplementary equipment depends on the ESCR value provided for the connection point, with higher requirements applying as the ESCR value falls. Importantly, the requirements do not prevent the supplementary equipment from also being used commercially, for example by participating in the reserve markets, provided its market use does not compromise the stabilising performance the requirements demand.
Effect on the connection process
Fingrid provides the ESCR value to the connecting party as part of the specific study evaluation under chapter 5 of VJV2024, before the connection agreement is concluded. The connecting party must specifically request this evaluation from Fingrid, regardless of whether the power plant is to be connected to Fingrid’s own grid or to another network operator’s grid.
The assessments required under the new framework are formally carried out during stage 1 of the VJV2024 compliance verification process, but Fingrid recommends that connecting parties already confirm compliance with their equipment suppliers at stage 0, that is, before procuring equipment, using the power plant’s preliminary design values. An ESCR value provided by Fingrid is valid for 12 months. The supplementary equipment must be connected to the grid and able to operate within its minimum sizing requirements whenever the power plant operates at 50% or more of its rated power, and its construction and commissioning must be timed so that it is available when the power plant starts feeding active power into the grid, meaning the supplementary equipment generally needs to be built on the same timeline as the power plant itself.
Does the connecting party have to build the supplementary equipment itself?
A power plant may procure the required supplementary equipment as a service, for example from a BESS operator, provided that the equipment is a new storage facility that does not yet have its own connection agreement. However, an existing or already-under-construction BESS facility that already has a connection agreement cannot serve as the supplementary equipment, since it has already been accounted for in the ESCR value Fingrid has provided. Fingrid itself will not build such equipment for a fee, nor does it offer its own existing equipment for this purpose.
Where the supplementary equipment is procured as a service, the connecting party remains responsible for ensuring its availability throughout the power plant’s operating life. If the supplementary equipment is unavailable, the power plant’s output must be curtailed accordingly.
A sector already adapting to a changing connection landscape
The new specific study requirements arrive against the backdrop of a wider transformation of Finland’s grid connection landscape. As we reported last month, the Ministry of Economic Affairs and Employment has also sent out for consultation a draft amendment to the Electricity Market Act that would introduce a prioritisation model for grid connections, driven by surging connection demand from electrification, renewable generation and planned data centre capacity. The amendment to the Electricity Market Act is intended to enter into force on 1 January 2027 (see our earlier post, “New legislative proposal on priority connection procedure for the electricity grid – Consultation open until 9 October 2026“).
HPP Energy Team is closely following these developments and will keep you updated on further changes affecting grid connections in Finland.
