From The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH): “With new solar modules greenhouses run on their own energy”

From The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH)

Cécilia Carron

Plants use light waves from only a portion of the spectrum for photosynthesis – the remainder can be recovered and used to generate solar power. That’s the idea behind the solar modules developed by EPFL startup Voltiris. Following encouraging preliminary results, a new pilot installation was recently installed in Graubünden.

In Switzerland growing tomatoes and cucumbers and peppers and other light- and heat-intensive vegetables requires building a greenhouse – but operating one consumes a huge amount of power. Farmers have to carefully balance crop yields and economics with environmental concerns. “It costs more than CHF 1.5 million a year to heat a 5-hectare greenhouse,” says Nicolas Weber, the CEO of Voltiris. “And a greenhouse of that size emits roughly the same amount of CO2 per year as 2,000 people.” The Swiss federation of fruit & vegetable growers which cultivate several thousand hectares across the country has set a target of eliminating all fossil-fuel-based energy from its farming processes by 2040. The system developed by Voltiris can go a long way towards reaching that goal. Its technology is based on the fact that plants don’t use all of the waves contained in sunlight; the remaining ones can be concentrated onto photovoltaic (PV) cells to generate solar power. Voltiris’ system is lightweight and designed to track the sun’s movement across the sky, and boasts daily yields on par with conventional solar panels. The first vegetables grown under Voltiris’ system were harvested this summer through pilot tests carried out at two greenhouses in the cantons of Valais and Graubünden.

Red and blue for plants, and the rest for PV cells.

Sunlight is essential for growing crops, as plants need it for not just photosynthesis but also phototropism (what causes plants to grow in the direction of light) and photoperiodism (how organisms react to seasonal changes in the length of the day). But plants are selective about which parts of the spectrum they use, relying on red and blue light. Voltiris’ filters therefore let these wavelengths pass through, while directing the other wavelengths (green and near-infrared) towards PV cells where they’re converted into solar power. What’s more, the system generates this renewable energy without reducing crop yields, since plants still receive all of the sunlight they need.

The system consists of dichroic mirrors which show a different coloration depending on the observation condition. The color on the glass – reminiscent of the anti-glare coating used on eyeglasses – gives the mirrors an almost decorative feel as they change colors based on the light passing through them. Two patented inventions are what make Voltiris’ system unique and able to perform so well. The first is an optimized optical system that effectively concentrates sun light, and the second is a solar-tracking device designed for under-roof use, which extends the length of time the system can produce solar power by 40%. Thanks to these breakthroughs, the system can achieve yields similar to those of conventional solar panels but with only half the light waves – i.e., green and near-infrared light. “We plan to apply different treatments to the reflective glass based on the needs of specific crops, in order to improve our yields even further,” says Weber. The lightweight installation fits into the empty space between the roof of the greenhouse and the top of the plants.

Meeting 60–100% of a greenhouse’s energy needs

Pilot tests of the new system have showed that they should be able to cut the greenhouses’ CO2 emissions in half while providing between 60% and 100% of their energy needs depending of the heating system in place: “emission are not reduced to zero because our system will start to replace electricity, which is generally “cleaner” than gaz. “This translates into an environmental benefit but also a financial one, once the cost of the system has been recovered, which should take between four and seven years,” says Weber.

Voltiris’ innovation comes at an opportune time, as the Swiss federal government has rolled out incentives over the past few years to encourage greenhouse operators to reduce their reliance on fossil fuels for heating. These incentives include subsidies for clean-energy systems. But existing alternatives, such as wood, biofuel and geothermal power, probably won’t suffice. The technology developed by Voltiris therefore promises to be an attractive solution. The firm now plans to run more pilot tests in the Netherlands and Geneva before introducing its product on the market in the second half of 2023.

See the full article here .


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The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH) is a research institute and university in Lausanne, Switzerland, that specializes in natural sciences and engineering. It is one of the two Swiss Federal Institutes of Technology, and it has three main missions: education, research and technology transfer.

The QS World University Rankings ranks EPFL(CH) 14th in the world across all fields in their 2020/2021 ranking, whereas Times Higher Education World University Rankings ranks EPFL(CH) as the world’s 19th best school for Engineering and Technology in 2020.

EPFL(CH) is located in the French-speaking part of Switzerland; the sister institution in the German-speaking part of Switzerland is The Swiss Federal Institute of Technology ETH Zürich [Eidgenössische Technische Hochschule Zürich] (CH). Associated with several specialized research institutes, the two universities form The Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles Polytechniques Fédérales] (CH) which is directly dependent on the Federal Department of Economic Affairs, Education and Research. In connection with research and teaching activities, EPFL(CH) operates a nuclear reactor CROCUS; a Tokamak Fusion reactor; a Blue Gene/Q Supercomputer; and P3 bio-hazard facilities.

ETH Zürich, EPFL (Swiss Federal Institute of Technology in Lausanne) [École Polytechnique Fédérale de Lausanne](CH), and four associated research institutes form The Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles polytechniques fédérales] (CH) with the aim of collaborating on scientific projects.

The roots of modern-day EPFL(CH) can be traced back to the foundation of a private school under the name École Spéciale de Lausanne in 1853 at the initiative of Lois Rivier, a graduate of the École Centrale Paris (FR) and John Gay the then professor and rector of the Académie de Lausanne. At its inception it had only 11 students and the offices were located at Rue du Valentin in Lausanne. In 1869, it became the technical department of the public Académie de Lausanne. When the Académie was reorganized and acquired the status of a university in 1890, the technical faculty changed its name to École d’Ingénieurs de l’Université de Lausanne. In 1946, it was renamed the École polytechnique de l’Université de Lausanne (EPUL). In 1969, the EPUL was separated from the rest of the University of Lausanne and became a federal institute under its current name. EPFL(CH), like ETH Zürich (CH), is thus directly controlled by the Swiss federal government. In contrast, all other universities in Switzerland are controlled by their respective cantonal governments. Following the nomination of Patrick Aebischer as president in 2000, EPFL(CH) has started to develop into the field of life sciences. It absorbed the Swiss Institute for Experimental Cancer Research (ISREC) in 2008.

In 1946, there were 360 students. In 1969, EPFL(CH) had 1,400 students and 55 professors. In the past two decades the university has grown rapidly and as of 2012 roughly 14,000 people study or work on campus, about 9,300 of these being Bachelor, Master or PhD students. The environment at modern day EPFL(CH) is highly international with the school attracting students and researchers from all over the world. More than 125 countries are represented on the campus and the university has two official languages, French and English.


EPFL is organized into eight schools, themselves formed of institutes that group research units (laboratories or chairs) around common themes:

School of Basic Sciences
Institute of Mathematics
Institute of Chemical Sciences and Engineering
Institute of Physics
European Centre of Atomic and Molecular Computations
Bernoulli Center
Biomedical Imaging Research Center
Interdisciplinary Center for Electron Microscopy
MPG-EPFL Centre for Molecular Nanosciences and Technology
Swiss Plasma Center
Laboratory of Astrophysics

School of Engineering

Institute of Electrical Engineering
Institute of Mechanical Engineering
Institute of Materials
Institute of Microengineering
Institute of Bioengineering

School of Architecture, Civil and Environmental Engineering

Institute of Architecture
Civil Engineering Institute
Institute of Urban and Regional Sciences
Environmental Engineering Institute

School of Computer and Communication Sciences

Algorithms & Theoretical Computer Science
Artificial Intelligence & Machine Learning
Computational Biology
Computer Architecture & Integrated Systems
Data Management & Information Retrieval
Graphics & Vision
Human-Computer Interaction
Information & Communication Theory
Programming Languages & Formal Methods
Security & Cryptography
Signal & Image Processing

School of Life Sciences

Bachelor-Master Teaching Section in Life Sciences and Technologies
Brain Mind Institute
Institute of Bioengineering
Swiss Institute for Experimental Cancer Research
Global Health Institute
Ten Technology Platforms & Core Facilities (PTECH)
Center for Phenogenomics
NCCR Synaptic Bases of Mental Diseases

College of Management of Technology

Swiss Finance Institute at EPFL
Section of Management of Technology and Entrepreneurship
Institute of Technology and Public Policy
Institute of Management of Technology and Entrepreneurship
Section of Financial Engineering

College of Humanities

Human and social sciences teaching program

EPFL Middle East

Section of Energy Management and Sustainability

In addition to the eight schools there are seven closely related institutions

Swiss Cancer Centre
Center for Biomedical Imaging (CIBM)
Centre for Advanced Modelling Science (CADMOS)
École Cantonale d’art de Lausanne (ECAL)
Campus Biotech
Wyss Center for Bio- and Neuro-engineering
Swiss National Supercomputing Centre