HEDNO Announcement on the Acceptance of Applications for the Addition of Storage Units to existing and new RES stations in application of Article 40 of Law No. 5151/2024 (Government Gazette A’ 173/04.11.2024) through an independent converter

In implementation of Article 40 of Law No. 5151/2024—which introduced Article 11C, titled “Addition of Storage Units to Existing and New Renewable Energy Sources (RES) Stations,” into Law No. 4685/2020—the Network Operator informs interested parties that it is now accepting applications for the addition of storage systems to both existing and new RES stations, in accordance with paragraphs 1 and 2 of the newly added article. Furthermore, the Network Operator is also accepting applications for the supply of electricity from renewable energy sources via an independent converter for the Interconnected Grid, as provided under Article 11C of Law No. 4685/2020.

Connection requests shall be submitted exclusively via the online platform which requires login via GIS using the TAXISnet credentials of the requesting entity.

The following must be submitted as part of the connection request:

  1. A) Supporting documents
  2. B) A Letter of guarantee in accordance with the provisions outlined below:
  • A separate letter of guarantee is required for the addition of a storage system with an independent converter to a RES station. The guarantee amount will be calculated in accordance with paragraph 3 of Article 6 of Law No. 4951/2022, based on the nominal capacity of the independent converter in kVA (instead of kW as specified in paragraph 3 of Article 6), which shall be considered the maximum injection capacity of the storage system.
  • In the case of adding a battery with an independent converter to a RES station, Article 89A of Law No. 4951/2022, as in force, shall apply regarding the reduction of guarantee amounts for RES station owners.
  1. C) Annex III
  • For RES plants that are converted into plants under paragraph 11A of Article 10 of Law No. 4685/2020, the fields “Maximum Injection Capacity (kW)” and “Maximum Absorption Capacity (kW)” in Table 1.1 of Annex III are not required to be filled out.

Update of announcement – 19.01.2026

Pursuant to paragraph 5(c) of Article 11G of Law 4685/2020, as introduced by Article 56 of Law  5261/2025, the submission of a letter of guarantee is required, the amount of which is calculated under paragraph  5(c) as follows:

  • For the purpose of calculating the amount of the letter of guarantee for the addition of energy storage systems to existing PV plants, as well as to new PV plants under paragraph 11A of Article 10, the “requested capacity” is deemed to be the plant’s Maximum Output Power.
  • For the purpose of calculating the amount of the letter of guarantee for the addition of energy storage systems to existing PV plants, as well as to new PV plants under paragraph 11B of Article 10, the “requested capacity” is deemed to be the plant’s Maximum Injection Power. (Pursuant to point (e) of paragraph 1 of Article 19A of Law 4685/2020: “The Maximum Injection Power of a RES and CHP generation plant with storage systems may not exceed the Maximum Output Power of the RES and CHP plant and the Maximum Injection Power from the plant’s storage systems, whichever is higher.”)

Example:

Assume a PV plant with an installed capacity of 400 kW and a maximum output of 400 kW.

  • For the addition of an energy storage system and conversion of the plant into a plant under paragraph 11A of Article 10 of Law 4685/2020, the amount of the letter of guarantee will be calculated based on the plant’s Maximum Output Power, i.e. 400 kW.
  • For the addition of an energy storage system and conversion of the plant into a plant under paragraph 11B of Article 10 of Law 4685/2020, where the storage system has a Maximum Injection Power of 500 kW, the amount of the letter of guarantee will be calculated based on the plant’s Maximum Injection Power, i.e. 500 kW.

The above letter of guarantee must be submitted to HEDNO’s Network Customer Department at the following address: 23, Syggrou Ave., Athens.

Annex with technical equipment specifications

In both case (a) and case (b), the submission of Annex Ι or Annex ΙΙ with the technical specifications of the plant equipment is required.

The provisions under items B and C of the announcement dated 17.04.2025 are replaced by the provisions set out in this update.