Energy storage
Since its beginnings in Corsica, Corsica Sole has developed unique expertise in isolated territories and constrained power grids. Confronted at an early stage with the challenges of island networks — fragile infrastructure, heavy dependence on fossil fuels and fluctuations in generation — we rapidly had to master energy storage solutions. This pioneering experience made storage a central pillar of our know-how, well before it became a national and European priority.
In such environments, storage is not merely an add-on: it is essential to stabilise the grid, smooth renewable energy production and secure electricity supply.
In 2015, Corsica Sole emerged as a pioneer with the Alata power plant, the first in France to combine large-scale solar generation with battery storage. Since then, we have continued to develop innovative energy storage solutions, including:
- Hybrid systems combining solar generation and storage, such as at Alata;
- Stand-alone storage facilities dedicated to grid services, such as those at Prato in Corsica and Abondance on Réunion Island.
Building on the expertise acquired in island territories, Corsica Sole now deploys its know-how on the continental scale. Landmark projects have since been delivered, including the Deux-Acren storage plant in Belgium (100 MWh) — the largest storage facility in continental Europe at the time of its commissioning in 2022 — and more recently the Hertz 1 and Hertz 2 plants in Estonia (400 MWh), which contribute to strengthening the energy sovereignty of the Baltic States.
In 2025, Corsica Sole continues this growth momentum and confirms its position as a leading energy storage player in Europe, developing large-scale projects in support of the energy transition and the resilience of electricity networks.
Energy storage has become a cornerstone of the transition to a decarbonised power system. It addresses one of the main challenges of renewable energy: variability. Thanks to batteries, electricity produced when the sun is shining or the wind is blowing can be stored and then released when generation drops, ensuring a constant and reliable supply.
This ability to decouple production from consumption is crucial for the large-scale integration of renewable energies, reducing reliance on fossil fuels and strengthening the stability of electricity grids, both on islands and on the mainland.
Key benefits:
Corsica Sole continues to innovate, making energy storage a key lever of the energy transition and of territorial energy autonomy.
Two battery energy storage technologies
Storage co-located with a solar power plant
On a single site, the photovoltaic power plant directly supplies the batteries. The electricity stored is then reinjected into the grid when solar production decreases (evening, night-time or unfavourable weather conditions).
Objective: optimise solar generation and smooth production variability.
Benefit: optimisation of grid connection infrastructure and minimisation of losses linked to solar production peaks.
Stand-alone storage
Independent from any generation site, this system is connected directly to the electricity grid. It can operate at any time to meet the needs of the grid operator or to participate in electricity markets.
Objective: provide grid flexibility, regulate frequency and voltage, deliver fast reserve capacity, and optimise arbitrage between electricity purchase and sale based on market prices.
Benefit: shift electricity produced during solar peaks (afternoon) to periods of high demand (morning and evening) and relieve local grid constraints.
Technologies and expertise
Our energy storage projects are primarily based on state-of-the-art lithium-ion batteries, recognised for their performance, reliability and long service life. These technologies deliver very fast response times and a high degree of operational flexibility, both of which are essential for modern power systems.
We systematically integrate intelligent Energy Management Systems (EMS), capable of controlling the batteries in real time according to:
- the needs of the electricity grid (frequency, voltage, local constraints),
- forecasts for renewable energy generation,
- price signals from electricity markets.
Each installation is designed on a bespoke basis, taking into account:
- the required power and capacity (discharge duration, response speed),
- the specific constraints of the public grid, in particular the ability to respond rapidly to relieve local congestion caused by high levels of local generation or consumption,
- the economic and environmental objectives defined with our institutional and industrial partners.
This integrated approach enables Corsica Sole to deploy robust, high-performance and scalable storage solutions, supporting grid stability, the large-scale integration of renewable energy and the energy resilience of territories.
Flagship projects
- Alata, Corsica: the first large-scale solar-plus-storage power plant in France,
- Prato, Corsica: a stand-alone storage system dedicated to stabilising the island grid,
- Abondance, La Réunion: stand-alone storage in a non-interconnected zone (ZNI), optimising the integration of local renewable energies,
- Deux-Acren, Belgium: 100 MWh, the largest battery storage plant in continental Europe at the time of commissioning,
- Hertz 1 and Hertz 2, Estonia: 400 MWh, strengthening the energy sovereignty of the Baltic states and supporting the ramp-up of renewable energy generation,
- New continental projects: several sites under development in mainland France, notably to support RTE in securing the power system and to operate on capacity and energy markets.
In France and across Europe, Corsica Sole continues to develop large-scale projects to increase available storage capacity and meet the growing need for flexibility in electricity networks.
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Challenges and outlook
Energy storage is far more than a complementary technology: it is a key enabler of a fully renewable electricity system.
In France, it helps secure electricity supply, enables greater integration of solar and wind power, and reduces CO₂ emissions.
Across Europe, it plays a strategic role by absorbing peaks in renewable generation and responding to the increasing volatility of electricity markets.
By 2030, Corsica Sole aims to deploy more than 1.5 GW of storage capacity, building on:
- ever more high-performance technologies,
- innovative business models,
- strong partnerships with grid operators and local stakeholders.
Our vision: to make energy storage a cornerstone of energy autonomy, serving territories and supporting the transition to a low-carbon energy system.