Designing solar steering light for sustainable horticulture

During this project, a light recipe combining two emitters to convert sunlight into an optimised spectrum for increased plant yield was successfully developed. The production of light-shaping foils demanded the scaling of in-house production of nanomaterials, which even surpassed our initial targets. We successfully produced A4-sized foils with partner Renolit, which we scaled up to a 5m² prototype foil produced in-house. The A4 foil was tested on a simple photosynthetic organism, cyanobacteria, at lab-scale, and we saw a substantial yield increase of 45% - growers get excited by just 1%. This promises that spectral selective shading for red-sensitive pigments, which are present in most crops, is highly effective.

To reach further validation in commercial horticulture, we need to upscale production to kg-scale and perform weathering tests to understand any potential degradation or leaching of the foils. This is a priority project for us as the sustainability and lifetime of our foils are of utmost importance and necessary to be well-studied before integration into greenhouses. Our continuous increase of production scale has yielded a roadmap to reach the targeted large scale, but has also revealed challenges in further scaleup that need to be overcome for ultimate prototyping in greenhouses. Our ongoing collaboration with a climate screen producer provides the necessary expertise for developing a suitable light recipe and foil for horticultural applications.

Horticulture crops and plants use only a limited part of the solar spectrum for their growth, the photosynthetically active radiation (PAR); even within PAR, different spectral regions have different functionality for plant growth, and so different light spectra are used to influence different properties of the plant, such as leaves, fruiting, longer stems and other plant properties. Artificial lighting, typically with LEDs, has been used to provide these specified spectra per plant, defined by their light recipe. This light is called steering light. While the natural sunlight provides a much more sustainable and abundant form of energy, however, the solar spectrum is not tuned towards specific plant needs. In this project, we capitalize on recent breakthroughs in nanoscience to optimally shape the solar spectrum, and produce a spectrally selective steering light, i.e. convert the energy of the entire solar spectrum into a spectrum most useful for agriculture and plant growth to utilize the sustainable solar energy to its fullest, and save on artificial lighting and electricity. We will take advantage of the developed light recipes and create a sustainable alternative to LED steering light, using nanomaterials to optimally shape the natural sunlight spectrum, while maintaining the increased yields. As a proof of concept, we are targeting the compactness of ornamental plants and seek to steer the plants’ growth to reduce leaf extension and thus be more valuable. To realize this project the Peter Schall group at the UvA leads this effort together with the university spinout, SolarFoil, whose expertise lies in the development of spectral conversion layers for horticulture. Renolit - a plastic manufacturer and Chemtrix, expert in flow synthesis, provide expertise and technical support to scale the foil, while Ludvig-Svensson, a pioneer in greenhouse climate screens, provides the desired light specifications and tests the foil in a controlled setting.