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Connection to the main grid

Fingrid's services: Connection to the main grid
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We implement main grid connections based on our customers need and ensure that the main grid and customer networks are compatible. We guarantee you electricity transmission capability at the connection points.

Connecting to the main grid has multiple steps. Connections are planned at the early phase in cooperation with the customer. Based on the information gathered from the customer, our experts examine customer connection possibilities and agree on the connection solution together with customer. When planning the connection solution, we take into consideration the reliability of the grid, transmission capacity, electrical safety, environmental effects as well as overall costs. Fingrid’s General Connection Terms (YLE) defines requirements for main grid connections.

During the connection planning phase, more detailed connection plans are required. Customer checks the plans with Fingrid, after which construction work can begin. Commissioning of the connection is agreed in good time with Fingrid’s operational organisation.

With up-to-date technical information exchange we ensure the best possible and technically safe result.

Planning a new connection

If you’re planning a connection to the main grid, please inform us of the necessary technical details by filling the new grid connection form.


Connectivity refers to the technical suitability of the connection to the main grid. In order to determine connectivity, the customer must send Fingrid a connection enquiry via Fingrid’s map service. When connection enquiries are received by the map service, they are taken into consideration when the network is planned, and customers are always responded by email as soon possible.

Technical data and conditions of the connection are examined with the customer as early as possible in the project. Careful preparations ensure the technical feasibility of the connection before actual planning begins and prior to the acquisition of any land. A new connection may not unreasonably weaken the usability of the main grid and the connections of other customers.

Depending on the connection site and projects being connected, there may be some limitations for connectivity. The volume of the power to be connected also depends on the location of other projects in the same region. Connectivity and main grid capacity are confirmed in the agreement phase.
If a new connection causes changes in the main grid, this must be taken into account when scheduling the customer’s project.

Switchyard connection

A switchyard connection means a connection to a 400, 220 or 110 kV main grid switchyard. If planned connections are located close to a switchyard, they must be connected directly to the switchyard and not to a transmission line.

Connection solution                              Connected power

400 kV switchyard                                  250 MW or more

110 kV or 220 kV switchyard                 Less than 250 MW

110 kV transmission line connection

The main grid transmission lines in Finland are long, and switchyards are far apart due to the geographic transmission distances. On a case-by-case basis, connections to the 110-kilovolt transmission line are allowed, taking into consideration the available transmission capacity on the line and the other technical terms. The transmission line connection is planned together with Fingrid, taking into account the transmission capacity and the system security requirements in the area. The customer is responsible for planning and constructing the electrical installations and transmission lines that will remain in its ownership. For system security reasons, connections are not permitted to the 400- and 220-kilovolt transmission lines.

A transmission line connection means connecting a branch line or a substation connection with a switching device solution to a 110-kilovolt main grid transmission line. The largest permitted nominal size for a transformer connected to a transmission line connection is 40 MVA and the smallest short circuit reactance is 48,0 ohms.  A maximum of 65 MVA transforming capacity can be connected to a single connection point provided that this is permitted by the transmission capacity. Within the separately specified requirements, a single 63/31,5/31,5 MVA three winding transformer may also be used.

Small synchronous generators of less than 5 MW or converter connected power plants of up to 30 MW can be connected to a transmission line connection, and the short-circuit current fed into the main grid can be no more than 1.2 times the power plant’s nominal current. The connection must be equipped with disconnectors implemented on the technical basis defined for each case individually. 

The transmission capacity of the transmission line and the regional system security of the main grid must always be verified with the transmission system operator. The necessary grid analyses are always performed with the customer.


During the connection planning phase, the customer compiles detailed plans for its connection and delivers them along with the other necessary technical data to Fingrid for review. Planning should be started well in advance in projects where connection requires a transmission line which is constructed by the customer.

The information required from the customer in the planning phase are a substation layout and elevation drawing, single line diagram, realisation of energy metering, earthing system, coordinates, information on the transformer and the branch line, information on the relay protection and communication link.

To support the customer in planning, Fingrid provides information about the short-circuit current and earth fault current as well as the basic requirements for the protection system. The fault current values can be requested directly from vikavirrat@fingrid.fi. The customer is responsible for the installation work for its substation equipment and the specification of their technical values.

Fingrid is responsible for arranging the energy metering and for providing an energy meter to the substation in question. The customer will reserve space for energy meters and submit to Fingrid’s contact person an energy measuring circuit diagram for the planning of measurements.

Agreement on the connection

Main grid connections are agreed upon by making a connection agreement. The prerequisites for the agreement are that the land-use plan (or decision on the need for planning) required by the project is legally valid, the connection solution corresponds to the technical terms, and any expropriation permit applications that may be required for the connecting line have been submitted to the authorities. For power plant connections, a further prerequisite for the agreement is that the land-use plan (or decision on the need for planning) for the power plant is legally valid, along with the building permits. Fingrid’s General Connection Terms and Specifications for the Operational Performance of Power Generating Facilities are part of the connection agreement signed with the customer.

The connection agreement takes effect when the parties have signed it and the customer has paid the connection fee specified in the agreement. If the connection fee is not paid until the due date, Fingrid has the right to terminate the contract immediately.

The customer’s high-voltage line shall be completed within 36 months of signing the connection agreement. Fingrid shall be entitled to terminate the agreement and release the network capacity for other customers if the connection is not commissioned as agreed.

The connection agreement shall be valid indefinitely, with a three-year termination period and a minimum term of 15 years from the date of signature.

If the customer’s connection requires construction of a new substation in the main grid, the customer pays the connection fee in the manner outlined in the project agreement.


If necessary, we will issue a technical statement to the customer on the potential connection solution. A statement may be given if the initiative for land-use planning is approved or a decision concerning the planning solution has been made.

Main grid contract

Electricity transmission is agreed upon by means of a main grid contract before the main grid connection is commissioned and energised. The contract requires the technical terms for the main grid connection to be fulfilled and the customer to have a valid connection agreement and an open electricity supplier agreement.

Letter of Intent

Fingrid and project developer can sign a Letter of Intent (LOI) for projects that will be connected with 400 kV. Signing the LOI requires that the EIA program of the project is published. Also rights for project area needs to be granted (i.e. land lease agreement or exclusivity for the water area). The LOI describes the process that leads to the main grid connection and connection agreement. The LOI does not guarantee grid connection or reserve grid connection capacity to the Customer.


Once the plans have been approved, construction can begin. The customer delivers the project implementation schedule, final documents and electrical values to Fingrid according to the KJV2018 document. The documentation should be delivered in the My Fingrid service.

Agreement concerning electricity transmission outages in the main grid during construction of the connection must be reached as early as possible. The connection need must be reported as early as possible and no later than 21 days before the proposed connection date. The main grid operation specialists who are responsible for the planning of outages and connections will inform the customer of the connection date.

Additionally, it is required that when operating in or in the immediate vicinity of Fingrid's transmission line’s right-of-way, a safety notification must always be filled in the Fingrid Safety Declaration Service.

Before commissioning, the customer must perform a commissioning inspection on the electrical installation of the connection. Fingrid’s operation specialist will examine the new connection and verify that the connection corresponds to the plans agreed with Fingrid earlier and that the connection can be energised. A protocol of the commissioning inspection is drawn up and sent to the operation specialist. Additionally, all documentation in the planning phase of KJV2018 should be delivered and accepted in My Fingrid service.

A period of time is reserved for construction in accordance with the terms of the connection agreement. Agreement concerning electricity transmission outages in the main grid during construction of the connection must be reached as early as possible.


The switching need must be reported as early as possible and no later than 21 days before the proposed switching date. The main grid operation specialists who are responsible for the planning of outages and connections will inform the customer of the switching date.



Connecting to the main grid & main grid transmission:

Petri Parviainen
Unit Manager
tel. +358 30 395 5282

Jarno Sederlund
Customer Manager
tel. +358 30 395 4251

Antero Reilander
Customer Manager
tel. +358 30 395 4199

Onni Härmä
Customer Manager
tel. +358 30 395 4299

Markus Talka
Customer Manager
tel. +358 30 395 5160

Grid code specifications:

Lasse Linnamaa
Expert, Power Plants
tel. +358 30 395 5362

Teemu Rissanen
 tel. +358303954287

Offshore wind connections:

Laura Ihamäki

Offshore expert
tel. +358 30 395 5166