SolarFoil: converting the sunlight to increase production and greenhouse sustainability

Trials have been conducted on micro-algae, which allowed small-scale experiments in the labs with 1m2-size Solarfoils.

A Dutch start-up is working on a thin, transparent, nanomaterial-based foil that converts part of the light spectrum into light frequencies that plants can use. The first trials with micro-algae yielded promising results, but SolarFoil is still in its early stages, and its potential hasn’t been explored to the fullest, writes Paola Cassiano for FCI.

Let’s start with a short lesson in light. As water and nutrients, light is an essential resource for crop growth. Depending on the crop type, it has to be available for a minimum number of hours, not exceed certain maximum levels, and be of good quality.

During winter, the natural light source given by solar radiation is often insufficient for greenhouse production, especially in Northern Europe. On the contrary, the abundant light availability in the warmer season threatens greenhouse production in Southern European countries.

Solar Foil Concept.

Different solutions for opposite problems

Different solutions are adopted to overcome these opposite problems. In the last few years, most producers have fitted their greenhouses with LED lights to provide sufficient light levels in the winter months. Their use even allows light steering, which means creating light recipes by modifying the spectral composition to influence plant properties and increase yield quality.

Instead, where light is too abundant and shading the crops in summer is necessary, the most popular solutions have been the application of lime or paints to the upper surfaces of greenhouses, shade nettings and cloths.

The cons of these solutions

The fact that these solutions are so common clearly proves that they work. However, there are also some cons. For instance, the most important disadvantage of LED lights is energy consumption. Even if LEDs are undoubtedly much more efficient than high-pressure sodium (HPS) lamps and other metal halide lamps, they still require energy, and this can be interpreted as a feature to be improved to increase sustainability in greenhouses.

Additionally, LEDs contribute to nocturnal light pollution, which can cause several issues: interference with nearby airport operations, disturbing animal populations, impacting crops in the greenhouse proximity, and reducing the quality of life of neighbourhood residents by disrupting their sleep patterns (especially in countries with high population density, such as the Netherlands).

A few things could be improved regarding the application of lime, paints, shade nettings and cloths. Sometimes they cannot provide uniform shade, so they create variable environmental conditions in the greenhouse, reducing the quality of the harvested products. Some of them are vulnerable to precipitation, so they must be re-applied after rain, and removed at the end of the summer season, which means labour costs are involved. For all these reasons, there is a need to find alternative (or complementary) solutions for efficient, affordable, and sustainable light management in greenhouses.

SolarFoil has three promising applications

The good news is that a Dutch start-up is working on a technology to address these issues, and the first results seem promising. This technology is called SolarFoil: it is a transparent nanomaterial-based foil that converts part of the light spectrum into light frequencies that plants can use.

In other words, instead of providing artificial light, as LEDs do, SolarFoil transforms portions of natural light that plants cannot use for photosynthesis into helpful light. This suggests three promising applications: light optimisation (increasing light availability in winter), spectral selective shading (enhancing useful light while decreasing harmful light), and light steering (using light recipes to improve yield quality). One solution for several problems, both in the Northern and Southern European greenhouses, for winter and summer.

The company envisions a flexible foil being rolled out underneath the greenhouse roof or applied as part or coating of the glass roof, lasting about five years.

Nanomaterial technology

The characterising feature of SolarFoil is the nanomaterial technology. Compared to other products, nanomaterials allow much better control of light manipulation thanks to the small size of their particles. Changing the particle size will allow for delivering the optimal foil to each customer, depending on their needs (the crop they want to grow, the type of greenhouse they are working in, and their geographical location).

Also, nanomaterials are relatively cheap and easy to produce, which suggests they can produce an affordable and convenient technology for greenhouse producers.

Customers will have to wait, in any case. The development of SolarFoil is still in its early stages, and its potential has still to be fully explored. So far, trials have been conducted on micro-algae, which allowed small-scale experiments in the labs with 1 m2 size foils. The first results are encouraging since they showed a 10 per cent increase in the intensity of useable light for the algae.

Arnon Lesage, one of the founders of SolarFoil.

What’s next?

The company envisions a flexible foil being rolled out underneath the greenhouse roof or applied as part or coating of the glass roof, lasting about five years. And to increase the product’s sustainability, the researchers aim to create a circular economy model in which, after their use, foils are transformed to extract part of the constituent material and re-use it for new foils.

“In the short term (3-6 months), we are focussing on validation of the technology, in commercial environments focusing on light steering in a greenhouse and micro-algae with bio-reactors, and at a few m2 up to 10 m² of foil,” said Arnon Lesage, founder of SolarFoil. “Getting validation will help our goal to develop the technology further and enable us to continue to develop a foil for the more important use cases such as plastic greenhouses.”

With Arnon Lesage, PhD, the start-up was founded by Professor Peter Schall from Amsterdam University. The company was born as a spinoff of Amsterdam University in 2022. Nowadays, the team is completed with Yingying Tang, Ina Flaucher, and Jasmin Fisher, and more professionals will be involved in the short term, according to Lesage.

The start-up is looking for companies to work with. If interested, contact team@solar-foil.com

This article was first published in the June 2023 Edition of FloraCulture International.