Green electricity: Keolis Lyon adopts lightweight photovoltaic panels

Lightweight solar panels: an innovative solution for reducing carbon impact

Keolis Lyon, in partnership with SYTRAL Mobilités, the mobility authority for the Lyon area, is rolling out innovative projects aiming to reduce the carbon imprint of its infrastructure and activities. One focus of this low-carbon strategy consists in testing brand-new solutions for producing non-fossil energies.  

These tests pursue a dual objective: sourcing new clean energy opportunities for Keolis and, on the other hand, helping businesses develop, improve and industrialize their innovations.  

Keolis Lyon and SYTRAL Mobilités notably decided to install lightweight photovoltaic panels on the roof of the Le Thioley workshops (Metro D) in Vénissieux. Hundreds of square meters of roof space remain unexploited because their mechanical structures cannot support the weight of “conventional” photovoltaic solar panels.  

The lightweight solar panels are supplied by the French company CREAWATT. The feasibility study was conducted in 2023 across several potential sites, in partnership with Domunéo, a French expert in photovoltaic power plants, which will soon oversee the deployment and connection of this solution in late 2024. 

The lightweight panels tested here weigh 3.2 kg/m², compared with 18-20 kg/m² for a conventional panel. This significant difference means that solar power plants can be installed without any modification to the existing roof. This reduction in weight was made possible by using solar panels without glass or aluminum frames. In this case, the photovoltaic cells are welded together and are then encapsulated between layers of fiberglass and polyester resin. The panels are fastened with self-gripping strips developed by Velcro. Part of the tape is glued directly to the roofing, while a second part is glued to the panel so that it can be secured in place. 

These self-gripping strips were tested to withstand winds of up to 280 km/h. They are currently being assembled with the panels in France's Loiret region (Amilly, 45) by CREAWATT, the company that designed the system. The current goal is to assemble the entire panel from photovoltaic cells and other raw materials.  

On the labor side, CREAWATT promotes workforce integration by employing six disabled people in its 48-strong team. The company also employs 50 inmates from Orléans prison, with some staying on as employees after completing their sentences. 

76 lightweight solar panels for an annual output of 32 MWh and superior energy efficiency 

These solar panels are much lighter than standard rigid solar panels: each module weighs around 7 kg (for about 2m²), whereas a traditional structure weighs an average of 20 kg/m². This characteristic makes them better suited to structures that cannot support heavy loads: an undeniable asset for the buildings operated by Keolis Lyon. In addition, their flexibility and low thickness allow them to be installed on a variety of surfaces, with no need for any major structural modifications. Ease of installation is another key advantage of these panels. 

Moreover, the choice of these different materials makes it possible to reduce the greenhouse gas emissions generated during panel production, with a reduction of almost 20% in emissions compared to a conventional panel. 

The installation of 76 panels on the roof of the Le Thioley workshops will produce around 32 MWh of renewable energy per year, which will be used to power the site's own electricity supply. This setup is known as a self-consumption power plant. Admittedly, the yield of these innovative panels is slightly lower than that of conventional panels. But their major advantage lies in the fact that they can be installed on surfaces where it would not be possible to mount conventional rigid structures. 

Towards the widespread deployment of lightweight solar panels: next steps 

The project is progressing on schedule. Following preliminary site visits, two additional studies were carried out by an independent firm to certify the watertightness and structural suitability of the building during the month of October. 

In fall 2024, the lightweight photovoltaic panels are set to be installed over a one-week period, including connection to the low-voltage switchboard. The work will have to be carried out during a period of several consecutive days without rain, so that the glue required to attach the self-gripping strips can be applied. After validation of the preliminary studies, this phase should take place between mid-November and the end of December. 

The success of this pilot project will determine the next steps. If the results are positive, Keolis Lyon plans to deploy this technology on other network buildings to further reduce the company's carbon footprint and generate substantial long-term savings through the production of renewable energy. One question will also have to be decided at the end of the experiment: is it more appropriate to redesign a building's structure to install conventional panels, or to opt instead for these new lightweight panels? 

Keolis Lyon is demonstrating its commitment to sustainable innovation by exploring environmentally friendly energy solutions. This lightweight solar panel project represents a significant step towards a greener, more responsible future, in line with the CSR objectives of the company and its partners.