Connection Charges and Bonds

When a generator or demand customer executes a Connection Agreement with EirGrid a number of forms of security cover will be required and a number of charges will apply to the generator or demand customer under the agreement:

Connection Charges Bond: The connecting demand customer or generator must provide security in the form of a bond in respect of the connection charges set out in the Connection Agreement. It is calculated using the shallow costs of the connection. The Connection Charges Bond is due at Consents Issue Date and covers the balance of the Connection Charges yet to be paid.

Generator Connection Maximum Export Capacity (MEC) Bond: A generator Capacity Bond is often referred to as the Maximum Export Capacity (MEC) Bond. There are two MEC Bond Regimes; 1 and 2:

Bond Regime 1: Applicable to all generators to whom offers were issued prior to 25th August 2009 (CER/09/138) and to Non-Renewable Generators to whom transmission offers were issued prior to 1st July 2013.
Bond Regime 2: Applicable to all Renewable generators and non-Renewable generators connecting to the distribution system to whom offers were issued after 25th August 2009 and extended to all non-Renewable transmission connecting generators  to whom offers were issued after 1st July 2013 (CER/13/145). Non-Renewable Transmission connecting generators who received offers between 25th August 2009 and 1st July 2013 can choose between Bonding Regime 1 or 2.

See Bonding Regime table.

Further details of both Bond Regimes are covered in “Clause 24– Security under the Connection Agreement” of the General Conditions (CER/13/145).

Demand Connection - Maximum Import Capacity (MIC) Bond: A demand customer Capacity Bond is often referred to as the Maximum Import Capacity (MIC) Bond. Amongst other things, the bond may be drawn upon should the customer fail to construct their facility within the specified time frame (within reasonable tolerance). The bond amount is calculated at the network capacity charge x 18 (months) x MIC (MW) and put in place at Offer Execution.

A Connection Charge is levied in respect of the works required to connect a demand or generation customer to the system in accordance with current CER approved shallow connection policy.

EirGrid is required to identify the Least Cost Chargeable (LCC) connection. This is the least cost way of physically connecting to the transmission system (i.e. the least cost shallow connection works).  

For system reasons, EirGrid may choose an alternative connection method.  If this is the case, the customer will only be charged for the LCC connection. Alternatively, a customer may request a connection method other than the LCC. If this customer preferred connection method is acceptable to EirGrid, the customer will be liable for 100% of the costs of that connection method, including in additional deep reinforcements.
For Generation Customers: If the LCC is being built, the generator must pay 100% of the LCC.  Any deep reinforcements required to facilitate the connection are typically not charged to the generator.
For Demand Connections: If the LCC is being built, the demand customer must pay 50% of the LCC. Any deep reinforcements required to facilitate the connection are typically not charged to the customer.

For clarity, should the customer request a connection method other than the LCC, if this customer preferred connection is acceptable to EirGrid, the customer will be liable for 100% of the costs of that connection method.  If the customer preferred connection method results in additional deep reinforcements, the customer will also pay for these.

Transmission Generator and Demand customers are entitled to build or procure large elements of their own shallow connections in line with the Contestability of Connection Assets Paper approved by the CER. However, there will still be works carried out by EirGrid such as design approval, supervision, commissioning and final connection, for which connection charges will be payable.

On-Going Service Charges (OGSC) are levied on an annual basis for the operation and maintenance of transmission shallow connection assets required to connect a customer. As of 01 January 2021, following engagement with the Commission for Regulation of Utilities (CRU), EirGrid will no longer be charging On-Going Service Charges (OGSC) for the maintenance of transmission shallow connection assets. Alternatively these costs will be recovered through the standard maintenance arrangements under Transmission Use of System charges.

Pre-Energisation Data

In advance of generator connection, EirGrid usually requires additional technical information that would not have been available at the application stage.

Typically, this includes a clarification on the final choice of wind turbines (moving away from Assumed Data) or generator parameters and additional detailed information about dynamic modelling and harmonics.

EirGrid requires this information sufficiently in advance of generator connection to allow EirGrid to perform pre-connection technical studies. This means that the information is required 12 months in advance of connection. Further information is available here.

Dynamic Modelling

To effectively model the dynamic behaviour of new generators, we require an accurate Dynamic Model of the Facility. This Dynamic Model must be provided in two formats, A Specific User Defined model of the WTGs with site specific parameter settings, to be provided in PSS/E v33 and 2nd generation WECC generic models with the appropriate site specific parameter settings to reproduce with reasonable accuracy the dynamic behaviour of the wind farm during voltage or frequency disturbances in the Transmission System. This model shall be provided in PSS/E v34. If a WECC generic model is not available for the selected WTGs, a Laplace diagram shall be provided instead, including site specific time constants and gains.

It is also the customer’s responsibility to carry out a self-assessment study to demonstrate compliance with Fault Ride Through clauses in our Grid Code. We have published a template for the submission of Fault Ride Through Studies here.

Power System Harmonics

We monitor the quality of the power delivered on our power system. This is to make sure we supply high-quality electricity.

One of the things we look for is harmonics, which is a distortion to the electrical current and voltage waveforms. We monitor this to make sure the voltage distortion stays within the planning levels. You can find the planning levels in our grid code. If the distortion goes above these planning levels, electrical equipment could fail. 

Here, we publish our approach to identifying and managing harmonic issues. We will update this page when new information becomes available.

Two notes have been published by EirGrid dealing with Power Quality:

A note on Harmonic Issues
Power Quality Requirements for Connection to the Transmission System

Completed Application Forms

A list of all relevant applicants seeking connection to the Transmission system is published periodically*.

The list accounts for all generation, storage and interconnection applications, including wind, hydro, pumped storage, conventional etc, received by the Transmission System Operator (TSO), EirGrid.

*This list is currently under review. Please check back here soon.