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UK´s Energy Networks Association Engineering Recommendations

  • United Kingdom
  • Energy and infrastructure


The new ERECs G98 and G99

The UK´s Energy Networks Association (ENA) has introduced new standards for connection that apply to generation projects from 27 April 2019. ENA Engineering Recommendation (EREC) G59 has been replaced by EREC G99 (Requirements for the connection of generation equipment in parallel with public distribution networks on or after 27 April 2019), and EREC G98 (Requirements for the connection of Fully Type Tested Micro-generators (up to and including 16 A per phase) in parallel with public Low Voltage Distribution Networks on or after 27 April 2019) has replaced EREC G83.

The connections to which the new recommendations apply are equivalent to those to which the previously relied upon ERECs G59 and G83 applied, ie:

  • EREC G99 applies to generating plants that are single type tested generating units of less than 17kW per phase of 50kW three phase, or to multiple type tested generating units with a maximum aggregate capacity of less than 17kW per phase of 50kW three phase; and
  • EREC G98 applies to single or multiple (in a close geographic region) type tested generating units that are less than or equal to 16A per phase (ie a “micro-generator”).

The changes have been made to ensure compliance with the new requirements set out in the new EU Network Codes so as to “facilitate the harmonisation, integration and efficiency of the European electricity market” (European Network of Transmission System Operators for Electricity).

From now on, all contractual commitments relating to commissioning of grid connections will need to refer to the new requirements and developers will need to ensure that they are capable of satisfying the new requirements, including in terms of the works programme and cost.

Developers should also note that, as well as applying to new connections from 27 April 2019, any significant change to an existing installation (for example, replacement of an inverter) must be compliant with the new requirements, even if the connection as a whole was made pre-27 April 2019 and satisfied the requirements of G59 or G83.

G100 – Export Limitation

Linked to ERECs G59 and G83 (and their replacement recommendations G98 and G99), EREC G100 provides technical guidance on the connection of Export Limiting Schemes (ELS). Whilst not a new requirement, we have noticed an increased number of references to this EREC in project requirements.

The purpose of an ELS is to “limit the net site export to below an agreed maximum and are installed on the Customer’s side of the Connection Point”. Where the generating station to be connected to the Distribution System is capable of exceeding the export capacity that has been agreed by the Distribution Network Operator (DNO), an ELS may be installed to restrict the export to and import from the Distribution Network so as to ensure a balance on the network. The ELS acts as a protection mechanism by measuring the Active Power at specified points within the generating plant and either then restricting the generation output or balancing the customer’s demand so as to ensure the power exported to the network does not exceed the agreed export capacity.

Where an ELS will be installed, it needs to be incorporated into the overall works and commissioning programme. The DNO will need to be given the opportunity to witness the testing of the ELS, including that the ELS settings are “tamper proof”. Adequate notice of the planned commissioning dates will need to be shared with the DNO and the appropriate arrangements made to enable the DNO to witness the commissioning tests.

From a contractual perspective, ensuring all connection documentation and contracted capacity figures in power purchase agreements (PPA) reflect the limited capacity ensured by an ELS will be vital. Failing to specify the correct contracted capacity in a PPA could result in a breach of contract if the ELS restricts the capacity to a level lower than that specified, even if the actual capacity of the generating plant would be higher without the ELS.