France’s Charge in the Global Perovskite-Silicon Tandem Race

The global solar industry is undergoing a quiet but profound transformation. For decades, crystalline silicon solar cells have dominated the market, steadily improving in efficiency while dropping in cost. But silicon is approaching its physical limits-the theoretical maximum efficiency for a single-junction silicon cell is around 29%, and commercial modules today already operate in the 25–26% range. To push beyond this ceiling, the industry is turning to a disruptive innovation: perovskite-silicon tandem solar cells.

And France, perhaps unexpectedly, has emerged as one of the most formidable players in this global race.

The principle of tandem cells is quite simple. The solar cell containing one layer can utilize only a small part of sunlight because the silicon can capture only infrared light but loses a lot of energy absorbing ultraviolet and visible light. However, when we place on top of the silicon cell a second layer made of perovskite material, we are able to collect a much wider spectrum of sunlight. In other words, the solar efficiency may reach as high as 42% as opposed to only 20% of the silicon cell.

Perovskites represent an interesting type of material due to their unique structure. They are very promising because they can be processing with the help of low-temperature techniques. However, the problem is to bring laboratory results to the level of industrial products.

At the heart of France's tandem ambitions is the French Alternative Energies and Atomic Energy Commission (CEA), operating through its National Institute for Solar Energy (INES) in Chambéry. This is not a peripheral research effort-it is a full-scale industrial offensive.

In January 2025, CEA-INES and Italy's 3Sun-Europe's largest solar module manufacturer-announced a tandem perovskite-silicon cell with a certified efficiency of 30.8% on a 9 cm² area. What makes this achievement particularly significant is the cell size: while many international efficiency records are set on tiny 1 cm² lab samples, CEA and 3Sun achieved this performance on a 9 cm² cell, a scale far more representative of what can be transferred to industrial production. In just one year of collaboration, the teams improved efficiency by 2.4 percentage points, climbing from 28.4% in January 2024 to 30.8% in January 2025.

This record wasn't a one-off. By mid-2025, CEA had also achieved 30% efficiency on an 8.2 cm² cell certified by the European Solar Test Installation, and a remarkable 27.3% efficiency on nearly 100 cm²-a result that places France among the world leaders in the efficiency-to-size ratio. Perhaps most importantly, reference tandem cells monitored outdoors between December 2024 and September 2025 showed less than 1% loss after nine months of real-world exposure. Stability has long been the Achilles' heel of perovskite technology; this result signals that the technology is maturing rapidly.

Apart from CEA-INES, IPVF stands out as one of the important ones in the French tandem network. In June 2026, the two organizations collaborated to achieve an amazing level of efficiency of 31% using a 4-cm2 perovskite-silicon tandem cell. The cell was made by combining the nanotextured silicon solar cell made at TU Delft with the perovskite cell developed at IPVF via the slot dye coating method. Thus, IPVF is now working on integrated systems that combine both cells to achieve even higher efficiencies.
IPVF has also achieved a noteworthy level of efficiency of 16.8% using a mini-module (10 cm × 10 cm in size) based on a bifacial perovskite solar cell. The institute plans to develop the mini-module further by scaling it up to a size of 60 cm × 30 cm.

France's tandem strategy extends well beyond research laboratories. A constellation of industrial projects is taking shape:

Voltec Solar, a French module manufacturer, secured €9.3 million from France's environmental agency Ademe to accelerate perovskite-silicon tandem panel production. Together with IPVF, Voltec is pursuing the "STAFF" (Souveraineté Industrielle tandem de Fabrication Française) project under the France 2030 initiative, aiming to establish a domestic manufacturing base for tandem technology. The partners have set ambitious targets: market introduction by 2025 and production capacity scaling to 5 GW by 2030.

HoloSolis, another French solar developer, is building a 5 GW solar module factory in Sarreguemines, northeastern France, scheduled to begin production in 2027. While the factory will initially use TOPCon silicon technology, HoloSolis has made it clear that its ambitions extend to perovskite-silicon tandem cells, actively positioning itself for the industry's next performance leap.

Meanwhile, CEA's partnership with 3Sun-which has opened Europe's first gigafactory for high-efficiency heterojunction panels in Sicily, with a planned capacity of 3 GW-creates a powerful Franco-Italian axis for tandem industrialization.

The implications of France's tandem push extend far beyond academic bragging rights. Replacing current silicon technologies (25–26% efficiency) with tandem cells reaching 30–31% would increase electricity production by more than 20% while reducing land use and CO₂ impact by approximately the same margin. In a world racing to decarbonize, these numbers are transformative.

There is also a strategic dimension. As CEA's François Legalland put it: "The dominance of photovoltaic module production by Asia is not inevitable. Research institutions and industrial players can still be competitive in Europe. This is excellent news for our industrial and energy sovereignty". France is not just chasing efficiency records-it is chasing manufacturing independence.

France is not the only participant in this effort. Oxford PV (UK-Germany), Qcells (South Korea-Germany), and a multitude of Chinese and American corporations are engaged in similar tandem technologies. The global perovskite-silicon battery market, with a size of around $167 million in 2025, is expected to attain $1.875 billion by 2032 with CAGR of 42.1%.
Nevertheless, France has occupied a special place in this race. France presents an unquenchable combination of leading research centers (CEA-INES, IPVF), extensive public sector funding (France 2030, Ademe) and an increasing number of private sector investors (Voltec, HoloSolis, 3Sun), working in one direction. The goal of "Tandem Made in France" is transformed into an operational reality.

Challenges remain. Scaling up to full-size modules while maintaining efficiency, ensuring long-term durability, and driving down costs are formidable hurdles. But the trajectory is clear. In just a few years, France has transformed from a follower in solar manufacturing to a leader in the next generation of photovoltaic technology. The global perovskite-silicon tandem race is far from over-but France has firmly established itself as a contender to watch.