Harvesting electricity as well as salad

Voltiris develops photovoltaic modules for glass greenhouses, enabling electricity generation without reducing crop productivity. The technology transmits light needed for photosynthesis while converting the rest into energy. Installed inside greenhouses, it requires no building permits. Growers can adopt the solution through long-term energy contracts, avoiding large upfront investments. Learn more about how Voltiris' spectral mirrors reduce the ecological footprint of agriculture.

Greenhouses allow vegetables and salads to be grown all year round, even in more northern regions and are intended to reduce CO2-intensive transport. However, the gas and electricity consumption of the heating systems harms the carbon footprint. In Switzerland, the glass structures used for agricultural purposes cover an area of about 500 hectares. They are located in sunny areas and would therefore be ideal for photovoltaic (PV) systems. However, conventional PV modules would reduce the amount of light received by the plants in the greenhouses.

Voltiris' team, led by CEO and co-founder Nicolas Weber, has now developed a system of dichroic mirrors that split the incoming sunlight into spectral components. Mounted in a greenhouse, the system provides the plants with the components they need for photosynthesis and directs the unused light onto solar panels.

This enables vegetable producers to reduce their operational CO2 emissions while maintaining the same harvest volume. What's more: In contrast to solar systems on the roof, the mirrors can usually be installed without an official building permit.

To date, the cleantech startup has put almost 500 modules into operation in 14 greenhouses in five countries. Contracts for 3,000 more have been signed. “We have definitely started the scaling phase, and a FIT loan of CHF 500,000 is giving us an additional boost,” says Weber.

Initial sales partnerships with greenhouse equipment suppliers have been established. The next step is to establish a stable supply chain for the individual components. The EPFL spin-off is also exploring additional applications for its mirrors in greenhouses. “Initial assumptions, which have not yet been scientifically confirmed, give us hope that the growing conditions in greenhouses can not only be maintained with spectral filters, but even improved,” explains Weber.

The added value as an alternative power source has been calculated: if the technology were used in all greenhouses in Switzerland, it would save as much CO2 as is emitted by 18,000 households annually.

They turn greenhouses into solar power plants: Dominik Blaser, Jonas Roch, and Nicolas Weber (from left to right) from Voltiris

This article was first published in the TOP 100 Swiss Startup Magazine 2024.