The "Ai Stratis- Green Island" project is based on the operation of a hybrid RES station, which is combined with an energy storage system, ensuring the stability and reliability of the island's electricity supply.

The main components of the Hybrid Power Station (HPS) are:

  • An ENERCON E-44 wind turbine with a nominal capacity of 900 kW, equipped with a variable-speed synchronous generator, a rotor diameter of 44 m, and with a tower height of 55 m.
  • Photovoltaic (PV) panels with a nominal capacity of 226.8 kWp (four hundred sixteen (416) PV panels, each with a nominal capacity of 545 Wp) and four (4) inverters.
  • An electrical energy storage system (Battery Energy Storage System - BESS) consisting mainly of:
    • -  Lithium-ion batteries (Li-ion), MEGAPACK/TESLA type, with a total nominal capacity of 2,560 kWh,
    • - Bidirectional inverters (Tesla) with a total maximum power of 1,680 kVA, and Hybrid Power Station (HPS) internal management system (Tesla Site Controller) for the management of the electrical energy within the island's system in real time.

The energy management of the hybrid station is carried out through an advanced central control and supervision system, which monitors the production of electricity in real time, dynamically covering demand and channeling the excess renewable energy into an integrated District Heating System (DHS), which serves the residences of the settlement.

The main components of the District Heating System (DHS) are:

  • A heat generation station with three (3) electric boilers with a total capacity of 1,005 kW, including a continuous power regulation system,
  • Four (4) hot water storage tanks with a total capacity of 500 m3,
  • Recirculation pumps and a control system,
  • Connection substations and an underground distribution network,
  • An auxiliary conventional fuel boiler, to be used during periods when stored thermal energy in the storage tanks or surplus energy from the RES is unavailable.

The District Heating System (DHS) is integrated and includes the central production devices (electric boilers and conventional fuel boiler) and heat storage (hot water tanks), as well as the network for distributing thermal energy to end users. It also includes the building infrastructure for housing the equipment.

The implementation of the project ‘Hybrid System for the Production of Electrical and Thermal Energy from RES in the island of Agios Efstratios’ was awarded to TERNA ENERGY through an Open Tender conducted by the Center for Renewable Energy Sources and Saving (CRES).

Diagram of the Electricity Production and Thermal Energy System of Agios Efstratios
PV station
Hybrid station energy management system
Wind turbine Ε44-900
Battery Energy Storage System (BESS)
Central Station – District Heating System (DHS)
Central Station – District Heating System (DHS)