If silicon-based solar panels are so clean, why do they produce so much toxic waste?

Organic and bio-based solar cells to the rescue.

Ollie Cotsaftis
4 min readMar 30, 2021

Promises about harnessing energy from the sun can be traced all the way back to 1839. And in 1884, American inventor Charles Fritts installed the first solar panels on a rooftop in New York City.

Image © A brief history of solar panels, Smithsonian magazine, 2019

Today, Australia leads the world in solar per capita but… the problem of solar panel disposal “will explode with full force in two or three decades and wreck the environment”. Silicon-based solar panels produce indeed a “huge amount of waste and they are not easy to recycle.” (Forbes, 2018). Fortunately, alternatives such as carbon-based, Organic PhotoVoltaic (OPV) cells already exist.

In 2015, the Expo Milano German pavilion by Schmidhuber used OPV cells to generate energy from the sun.

And in 2019, Brazilian cosmetic Natura covered its headquarters with 1,800 sqm of OPV film — making the building one of the few energy-positive buildings in the world.

Images © Sunew/Natura, 2019

Made of non-toxic and recyclable materials, carbon-based OPV films are thin, light, flexible, durable, semi-transparent, and cheap — offering huge potential for innovation in design, architecture, construction, urban furniture and mobility projects.

“Because the carbon-based materials can be dissolved in a solvent, they can then be printed onto almost any material of any shape — using even the simplest inkjet printer. The panels are even flexible enough to be printed onto clothing — in the future we could be walking around wearing solar panels printed on our hats, coats and backpacks”, said Dr Wallace Wong, of the University of Melbourne’s Bio21 Institute and School of Chemistry (Bio21).

In 2019 also, a few of my students and I started researching organic solar cells; then designed a speculative sun-responsive skyscraper's envelope covered in red-coloured OPV films. This project was presented during the 2020 NGV Melbourne Design Week, in an exhibition aiming to showcase the possibilities of organic materials and bio-based technologies in the built environment.

Image © BioCities exhibition, 2020

The red colour was used discursively because silicon-based solar cells traditionally do not absorb red and near-infrared light efficiently, but carbon-based cells are most effective at capturing sunlight in the near-infrared region.

Solar energy distribution and capture. Image © Gerard Charles Dismukes, 2006

This is one of the reasons why OPVs currently produce less energy than silicon-based solar cells as near-infrared light is made up of lower energy photons (i.e., longer wavelengths) than the rest of the absorption spectrum.

OPVs, however, could be engineered to maximise the absorption of high-energy photons—from near-UV to blue/yellow light. Such an OPV would be able to produce more energy and would most likely look red to the human eye.

More recently, a new generation of organic solar panels made out of crop waste is showing even bigger potential than OPVs. These bio-based organic panels are able to “produce energy close to 50% of the time according to preliminary testing, compared to 15 to 22% on average in standard (silicon-based) solar panels”. Biodesign at its best.

Solar panels made from food waste win inaugural James Dyson Sustainability Award, 2020

Silver bullets to protect and regenerate the environment do not exist.

As we are transitioning to a circular and regenerative economy, we must question the use of current ‘green’ technologies that may or will create more issues than generate benefits in the long run.

Dr Olivier Cotsaftis (PhD, MBA) is a post-disciplinary researcher-practitioner exploring pathways towards regenerative and more-than-human urban futures. At RMIT University School of Design, his work focuses on unlocking practical and scalable potentials for sustainable urban development, specifically in the areas of biomaterials and climate adaptation of the public place. Before joining RMIT, Ollie spent 10 years in Industry, engaging with start-ups, not-for-profits, governments and blue-chip companies. He was a design lead at Fjord Design and Innovation and the founder of future ensemble studio. Ollie is also an editorial board member for Research Methods: Biotechnology Design (Cambridge Press, UK).

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Ollie Cotsaftis

System-led, Place-based, Material-driven — and with a love for words.