Origins, supply chain, market potential: everything you need to know about photovoltaic panels on French warehouses

China has been considered the world’s factory for several years. The photovoltaic panels installed on warehouse rooftops in France are a good illustration of this image. “More than 90% of these modules have been manufactured in the People’s Republic of China for around ten years because they perform as well as European models in terms of output while being more financially competitive,” notes Jean Damian, vice president of the photovoltaic trades group (GMPV-FFB) and director of Soprasolar, Soprema’s subsidiary that installs rooftop photovoltaic panels.

But what about the carbon footprint? “A module accounts for only 15% of the carbon footprint of a rooftop solar power plant,” says Jean Damian. “The remaining 85% comes from the integration system that allows the panels to rest on the roof—100% made in France at Soprasolar and manufactured in France or Western Europe by our peers—from electrical converters, which can be produced in China but also in France or North America, and from technical and administrative engineering, which cannot be offshored.”

As for the specific footprint of photovoltaic panels, it should also be put into perspective, according to SopraSolar’s director: “A module is an assembly of different components, primarily photovoltaic cells, which are finely cut silicon wafers. However, these are no longer produced in France because the raw material comes largely from China. Photovoltaic panels assembled in France therefore have a carbon footprint close to that of finished modules coming from China.” Nevertheless, some project owners are keen to install made-in-Europe modules on the roofs of their warehouses. Lidl is one such example.

Over the past four years, 18 megawatt-peak (MWp) have been deployed on Lidl buildings in France, representing 90,000 m2 of rooftop and canopy surface area, in addition to the existing 50,000 m² of photovoltaic panels. No fewer than 10 additional MWp will be installed over the next four years on the retailer’s new logistics platforms in France.

“The photovoltaic panels we deploy are assembled in France by Voltec Solar, or in Spain or Germany for our other partner brands,” adds Eric Tiemeni Tiako, head of the Fluids and Energy division at Lidl France. “They cost around 15% more than those made entirely in China. We bear this additional cost because they allow us to take a responsible approach by favoring shorter supply chains.” Transported by truck, they are delivered to the construction site a few days before installation and commissioning by a specialized company. That company also purchases them according to the specifications set by the project owner as part of a tender process.

Chinese photovoltaic panels, for their part, follow the same logistics chain as most mass-produced capital goods made in the country: transported by sea in containers, they are unloaded at major European ports before being carried by road directly to French construction sites or stored in warehouses. SopraSolar operates four warehouses for this purpose: two in the Lyon area, in Saint-Quentin-Fallavier, one near Orléans, and one outside Rennes. “They average 6,000 m2,” notes Jean Damian. “The photovoltaic panels stored there spend little time in inventory because demand is strong.” It has even surged in recent years.

“In 2023, we deployed our systems on 3.5 million m2 of building rooftops, including 1.5 million m2 of warehouses, representing approximately 150 MWp of capacity,” states SopraSolar’s director. “That is ten times more than five years ago.” This growth has required logistics to adapt: “We had only one warehouse in 2019. Since then, we have invested heavily in our supply chain, both in geographic coverage and in digitalization to improve order preparation, traceability, and more.”

And this may only be the beginning. In addition to the 5 million square meters that AFILOG members will deploy over the next five years on the roofs of their new warehouses, the potential of the existing market is substantial… but constrained. “Since launching our new made-in-Europe strategy four years ago, we have deployed photovoltaic panels on eight of our existing logistics platforms that could support them,” says Jonathan Saigault, head of Industrial Refrigeration, Fluids and Energy Services at Lidl France. “We were unable to equip some of our logistics platforms because of regulatory obstacles.” He elaborates: “These obstacles mainly concern certification of the photovoltaic roof-integration process for warehouses. Procedures with the CSTB are generally lengthy for our partners seeking to obtain the current technical assessment designation, which is more readily accepted by technical inspection bodies and insurers without having to pay significant additional premiums. In addition, after a certain age, roofs, even if initially PV Ready, are no longer considered as such without written proof following arduous laboratory testing; we experienced this at one of our logistics platforms in eastern France.” 

Some companies, such as Soprasolar, are seeking alternative solutions: “We have designed crystalline modules weighing 5 kilograms per m2, three times less than conventional photovoltaic panels, which can be bonded directly onto a new waterproofing system as part of a roof renovation,” explains Jean Damian. “This system has received a CSTB ATEX assessment and meets the three requirements of stability, strength and fire resistance. We therefore hope to cover 2 to 3 million m2 of existing building rooftops each year by 2028–2030.” The icing on the roof: this technological breakthrough provides a competitive advantage and makes production in France possible. Soprasolar’s modules are manufactured by the start-up Heliup in Chambéry. The monopoly held by Chinese photovoltaic panels on French warehouse rooftops is not inevitable. A few weeks ago, Minister for Industry and Energy Roland Lescure also mentioned two new gigafactory projects under development, in Sarreguemines and Fos-sur-Mer. Scheduled for 2025, these two plants are ultimately expected to produce 15 gigawatts (GW) of solar panels.