PhARRE: combining renewable energy generation, intelligent control and storage via second life batteries

At the end of 2020, the Syndicat Départemental d'Énergie et d'Équipement de la Vendée (SyDEV), in partnership with Bouygues Energies & Services, launched an innovative scheme to generate solar electricity stored in second-hand EV batteries. The project named PhARRE - Photovoltaic, Autoconsumption, Recharge and Electricity Network - already supports the electricity needs of the head office.

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Reducing the impact of energy consumption in buildings and recycling or reusing electric vehicle (EV) batteries are major environmental challenges for the years to come. Buildings account for 44% of the energy consumed in France. The growing use of electric vehicles could increase the weight of EV batteries needing to be recycled to 700,000 tonnes by 2035.


  • A virtuous and exemplary local initiative in the Vendée region and nationwide,
  • An innovative yet practical response to the challenges of making consumption greener and energy planning in the regions.

A duty to set an example in the Vendée region

For 10 years, SyDEV has been involved in energy saving operations at its office in La Roche-sur-Yon, reducing the impact of its energy consumption on the grid by 40%. As a public player in the energy transition, SyDEV aims to set an example by carrying out innovative projects, providing it with significant feedback that can be used by local authorities in the Vendée region. The aim of the PhARRE project was to test new ways of generating and storing energy, and to see how these solutions could be used within public buildings in the Vendée region.

PhARRE: improving energy efficiency at the SyDEV head office

The PhARRE project began with the installation of 200 m2 (39.5 kWp) solar panels on the roof. The electricity generated is used directly in the building below to reduce the impact of the building’s energy consumption on the grid. As the headquarters are for the most part offices, consumption is mainly during the day, i.e. when solar power can be generated. There may be surplus generation during the day, but also and above all at week-ends and during the holidays. For this reason, and to optimise the amount of electricity it uses itself, SyDEV has set up a storage system. The aim is to conserve these surpluses and reuse them at more opportune times, particularly to meet the recharging needs of its electric vehicle fleet of around ten cars.

In figures:

Giving a second life to electric vehicle batteries

The innovative nature of the PhARRE project also lies in the choice of storage solutions for this power. So as to further limit the environmental impact, EV batteries were chosen that had lost 25% of their storage capacity and therefore no longer met the vehicle’s autonomy requirements. Four first-generation Renault Kangoo ZE batteries were therefore installed underground – 48 kW/h of storage, the equivalent of one hour of consumption – to store the renewable energy produced. The PhARRE project extends the use of these batteries by 10 years by giving them a second life.

To overcome the challenges of the energy transition, we need to consume less and better and to use more renewable energy. Here we generate energy for local consumption. The experience we gain from this innovation will be used to benefit the region’s public buildings

explains Alain Leboeuf, President of SyDEV

Bouygues Energies & Services, partner in the intelligent management of energy needs

As part of the PhARRE project, SyDEV has signed an agreement with Bouygues Energies & Services to develop an intelligent building management solution.

A wholly-owned subsidiary of Bouygues Construction, Bouygues Energies & Services aims to be a player in the energy, digital and industrial transition. The company proposes ways to integrate energy performance throughout the life cycle of its clients’ infrastructure and service sector assets. By supporting SyDEV in this self-consumption and storage project, Bouygues Energies & Services is strengthening its partnership with the organisation by developing innovative solutions that meet its customers’ needs.

The energy transition will transform our society and our economy in the long term. The role of the Energy & Services division is to pave the way for energy and digital transitions and transform them into opportunities for our customers, with innovative solutions at the heart of the regions. We have to test these solutions locally. The PhARRE project is a perfect illustration of this

adds Pierre Vanstoflegatte, Managing Director of Bouygues Construction’s Energy & Services division

The two entities have also surrounded themselves with reliable partners to carry out the PhARRE project

The Renault Group is a pioneer and leader in electric vehicles in Europe, with over 200,000 vehicles on the road at the beginning of 2019. The head start and the experience acquired are encouraging the Renault Group to become even more involved in the entire electric vehicle ecosystem and the life cycle of batteries. Thanks to PhARRE, the group is improving its second-life offer, particularly in terms of collection, preparation, logistics, end-of-life management and finally recycling.

BeeBryte is a French start-up with a staff of around 20 people. It harnesses the extraordinary potential of the Internet of Things and artificial intelligence to make commercial and industrial buildings more energy efficient and smarter, to reduce their electricity bills and their carbon footprint. This is a chance to adapt its Energy Management System solution for second-life batteries, to develop its algorithms and to integrate it industrially with Bouygues Energies & Services with a view to deploying it widely in other smart grid buildings.

What next?

The next step will be to integrate intelligent control of vehicle recharging with the system already installed to enable optimised management of all electricity consumed on the site. There are also plans to replicate the installation in a Vendée municipality.

About SyDEV: SyDEV is the Syndicat Départemental d’Énergie de la Vendée, which encompasses all the municipalities and inter-municipalities of the Vendée region. It supports local authorities on all energy-related issues: electricity and gas distribution, public lighting, energy efficiency of buildings, clean mobility (electromobility, bioGNV and H2), and very high-speed broadband. It invests in the generation of renewable energy (wind, solar and methanisation) through SEM Vendée Énergie.

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