Storage for ensuring the stability of electricity grids


NW Joules designed and developed the JBox.

This French innovation ( Patent registered ) is the result of multidisciplinary expertise and is now recognized by the energy players as an innovative system in the strategic electricity storage industry.

A compact “all-in-one” device, the JBox is easy to install and to connect to the local distribution grid.

The system is constantly controlled and monitored to make it possible to extract and to inject the electricity into the grid rationally and as needed.

Starting from its design, it is intended to recycle the components of the JBox and, in particular, of its batteries at the end of the installation’s life.


It is extremely important to develop electricity storage in order to increase the share of renewable energies in the French energy mix and to secure electrical grids, facing increased consumption due to the rapid growth in energy use for data storage (data centers), air conditioning and electric mobility.

Since the electricity production must constantly adapt to the consumption, the regulatory and balancing tools, such as the JBox, have become essential to guarantee a reliable and constant supply of electricity into the grid.

NW Joules has been certified as a Balance Responsible Entity by the French Electricity Transmission Network (RTE), and the JBox complies with all environmental protection requirements.

The JBox of Jonzac, a pilot project in Charente-Maritime, a pioneering French region in the electricity storage

As a result of the Haute Saintonge territory’s desire to accelerate its energy transition, the JBox of Jonzac was commissioned on January 3, 2019, becoming the first operational JBox in France and the first non-experimental storage facility to be certified by the French Electricity Transmission Network (RTE).

Since its connection to the power grid, the JBox has been providing a frequency regulation service to the electrical system, thus contributing to a secure electricity supply.

The JBox was inaugurated on July 26, 2019 in the presence of numerous energy actors, including Jean-François Carenco, the President of the CRE, Dominique Ristori, the General Manager of the European Commission’s Department of Energy, Jean-Louis Borloo, a former Minister of State, Dominique Bussereau, the President of the Charente-Maritime department, Françoise Coutant, the Vice-President of the Nouvelle-Aquitaine region in charge of the energy transition, Claude Belot, the Mayor of Jonzac, and Jean-Michel Rapiteau, the President of the SEM Energie Midi Atlantique.

Installation of new JBox in 2020

10 JBox in Charente-Maritime

2 JBox in Guadeloupe
& 1 in French Guiana

The French Energy Regulatory Commission (CRE), which is responsible for the proper functioning of the electricity and gas markets in France in accordance with the objectives of the French national energy policy, has decided to set up an active electricity storage policy in non-interconnected areas (in French overseas territories and Corsica), with the goal of saving 370 million euros in 25 years on its contribution to public electricity services. In 2018, the JBox was awarded with the CRE tender three times.

9 JBox in Bretagne

The Energy Breizh Box Projet
The Energy Breizh Box project, led by NW Joules, has won the “Conversion – Storage” call for tenders organized by the Bretagne region and co-financed by the European Regional Development Fund (ERDF). The project requires the installation of 9 JBox throughout the Bretagne region.
The advantage of this program is to combine the storage capacity of 9 JBoxes at a regional level, while having the possibility to provide flexible power grid services locally, in addition to the installation of an ultra fast charging station for electric vehicles that is already planned at one of the sites.
NW Joules is a member of the SMILE (Smart Ideas to Link Energies) association aimed at the operational implementation of the energy transition and the green growth, co-chaired by the Bretagne and Pays de Loire regions.

NW Groupe has set a target to install 200 JBox by 2022