When we talk about innovation in Switzerland, precision watchmaking and finance are often the first sectors that come to mind. However, Switzerland is today a global superpower in an area that is much more crucial for our future: research and development of solar photovoltaic energy.
At the heart of this scientific revolution, two world-class French-speaking institutions stand out: EPFL (École Polytechnique Fédérale de Lausanne) and the CSEM (Swiss Center for Electronics and Microtechnology) based in Neuchâtel. Together, their labs don't just improve existing solar panels; they are redefining the limits of physics to create the next generation of solar cells.
The stakes are colossal. With limited roof space and strict climate targets dictated by the 2050 Energy Strategy, Switzerland needs solar panels capable of producing much more electricity on the same surface area. In this in-depth guide, Solar Panel Swiss experts take you behind the scenes of Swiss laboratories to understand how current innovations — including perovskite-silicon tandem cells — will transform the residential and commercial market over the next five years.
1. The Silicon Wall: Why We Need to Innovate?
To understand the feat of Swiss researchers, we must first understand the limits of current technology. Today, around 95% of solar panels installed on Swiss and global roofs are made from silicon.
The Shockley-Queisser limit
In quantum physics, there is a theoretical glass ceiling called the "Shockley-Queisser limit." It states that a solar cell composed of a single silicon junction will never be able to convert more than approximately 29 % from solar energy to electricity.
Silicon is excellent at absorbing red and infrared light, but it is very ineffective against blue (high energy) light. Much of the energy in blue photons is simply lost as heat.
Where are we today?
Today's best commercial solar panels (like those from SunPower or Meyer Burger) flirt with yields of 22 % to 24 %. We are therefore extremely close to the absolute physical limit of silicon. To continue to increase the power of the panels without increasing their size, a major technological breakthrough was required. This is where Switzerland comes into play.
2. The “Tandem” Revolution: The Marriage of Perovskite and Silicon
To break the silicon glass ceiling, EPFL and CSEM are working on a fascinating technology: tandem solar cell.
What is Perovskite?
Perovskite is not a new material in itself, but a crystal structure specific. In the 2010s, scientists discovered that organic-inorganic materials with this structure could be synthesized, and that they were exceptional semiconductors.
The advantages of perovskite are immense:
- It absorbs blue and green light extremely well.
- It can be manufactured at low temperature, in the form of ink or liquid solution, which potentially makes it very cheap to produce (unlike silicon which must be melted at more than 1'400°C).
How does a Tandem cell work? (The EPFL/CSEM approach)
The genius idea of the Swiss laboratories (notably under the leadership of the EPFL PV-Lab directed by Professor Christophe Ballif) is not to replace silicon, but to complete. A tandem cell is made up of two superimposed layers:
- The upper layer (Perovskite): It is placed facing the sun. It absorbs blue light (high energy) and lets red light through.
- The bottom layer (Silicon): It recovers the red and infrared light that the perovskite has allowed to filter through, and in turn converts it into electricity.
By dividing the spectral work in two, the tandem drastically reduces thermal losses. The theoretical yield limit suddenly goes from 29% (silicon alone) to more than 42 %.
3. World Records Broken in Switzerland
The ecosystem of Neuchâtel and Lausanne is the scene of a global race for efficiency records. For decades, breaking 30% efficiency for a non-concentrated solar cell seemed like a distant dream.
However, the joint team from the Photovoltaic Laboratory (PV-Lab) of EPFL and CSEM has literally shattered this ceiling, by developing perovskite-silicon tandem cells achieving certified efficiencies exceeding the 31 %, then the 32 % in the laboratory.
This feat was made possible thanks to careful nanometric engineering: smoothing the rough surface of the silicon (which resembles microscopic pyramids) to deposit a perfectly uniform layer of perovskite a few nanometers thick, without creating short circuits.
4. From the Lab to the Roof: The Challenges of Commercialization
Achieving 32% yield on a 1 cm² cell in a laboratory is a scientific victory. Producing millions of 2 m² solar panels guaranteed for 25 years under the Swiss snow is another. Technology is currently facing the bottleneck of industrialization.
A. Stability and Durability
Unlike silicon, which is virtually unalterable, perovskite is fragile. It degrades quickly when exposed to humidity, oxygen and strong temperature variations. Swiss researchers are working on advanced encapsulation techniques to ensure the panel will survive at least 25 years.
B. Scale-up
Depositing a liquid layer of perovskite on a microscopic surface is mastered. Doing this on kilometers of glass with a perfectly uniform thickness requires new industrial machines. CSEM works closely with European industry to adapt existing production lines.
C. The question of toxicity (Lead)
The most successful formulations of perovskite contain a tiny amount of lead (less than 1 gram per square meter). Although the quantity is microscopic, Swiss and European environmental regulations require proof that this lead cannot escape into nature, even if the panel is broken by hail. EPFL teams are working hard on “lead-free” perovskites.
5. What does this change for Swiss Owners? (Horizon 2028-2030)
The arrival of perovskite-silicon tandem panels on the commercial market (expected gradually over the next 3 to 5 years) will transform the solar economy in Switzerland.
More energy on small roofs
Swiss houses often have complex roofs, intersected by skylights or chimneys, providing limited space for photovoltaics.
- Today: A standard 2 m² panel produces approximately 400 to 430 Watts.
- Tomorrow (Tandem): The same 2 m² panel could produce more than 550 to 600 Watts.
This power density will allow many owners to achieve energy autonomy (to charge their electric car and power their heat pump) without the need for a huge roof.
Reduction in the cost of energy (LCOE)
By producing 30% more electricity for the same installation, wiring and labor costs, the return on investment of a solar installation in Switzerland will be further shortened.
6. Beyond Perovskite: Aesthetics and BIPV by CSEM
CSEM does not just look for gross yield. One of their greatest contributions concerns the BIPV (Building-Integrated Photovoltaics), or photovoltaics integrated into the building.
In Switzerland, where heritage protection (Heimatschutz) is strict, installing traditional black solar panels is often prohibited on historic buildings. CSEM has developed revolutionary technologies (such as nanometric filters) to create white, terracotta (red) solar panels, or perfectly integrated into the tiles.
By combining these aesthetic advances with the future power of perovskite cells, Switzerland is moving towards a future where each building facade, each tile, and each window will be an invisible electricity generator.
Conclusion: Switzerland, Energy Laboratory of the World
The joint work of EPFL and CSEM is not simple academic feats. They constitute the roadmap for the global energy transition. While the current market is dominated by silicon, Swiss solar research is preparing the next industrial breakthrough with the perovskite-silicon tandem revolution, guaranteeing buildings that are both beautiful and powerful.