A natural dye extracted from red onion skins may significantly improve the performance and durability of solar panels, according to researchers in Finland. The study focused on how this plant-based material enhances ultraviolet (UV) protection in solar cells, which are the essential components that make up solar panels.
Traditional solar panels rely on plastic-based coatings, such as polyvinyl fluoride (PVF) and polyethylene terephthalate (PET), to shield cells from UV damage. These petroleum-derived films help prevent long-term degradation, but pose environmental concerns due to their fossil fuel origins.
In search of more sustainable solutions, scientists have turned to nanocellulose—a biodegradable material made by breaking down plant fibers into nanoscale threads.
In a study published in ACS Applied Optical Materials, a team from the University of Turku combined nanocellulose with dye from red onion skin and found that the mixture provided strong UV protection while maintaining high light transmission.
Red onion dye outperforms conventional UV filters
The bio-based film blocked 99.9% of UV rays up to a wavelength of 400 nanometers (0.000015748 inches). Researchers noted that this red onion-based solution outperformed commonly used PET films in both protection and transparency.
Rustem Nizamov, a doctoral researcher involved in the study, said the findings offer a promising alternative for applications that demand sustainable materials without sacrificing efficiency.
The research team compared four versions of nanocellulose films, each treated with a different additive: red onion extract, lignin—a natural polymer found in plants—and iron ions. While all variations helped reduce UV exposure, the film containing red onion dye proved the most effective.
Solar panels must strike a balance between blocking harmful UV light and allowing visible and near-infrared light—between 700 and 1,200 nanometers (0.000027559 and 0.000047244 inches)—to reach the solar cells and generate power.
Some bio-based additives, like lignin, absorb too much visible light due to their darker color. For example, the study found lignin-treated films transmitted only 50% of light between 400 and 600 nanometers (0.000015748 and 0.000023622 inches) and peaked at 85% above 600 nanometers (0.000023622 inches).
Maintaining performance over time is key
By contrast, the red onion film maintained more than 80% transmission in the 650 to 1,100 nanometer range (0.000025591 and 0.000043307 inches), even after undergoing 1,000 hours of artificial light exposure—roughly equivalent to one year of sunlight in Central Europe.
Nizamov emphasized that long-term durability is essential for any material used in solar technology. He pointed out that some films, such as those treated with iron ions, lost their effectiveness after aging.
Beyond solar energy, the researchers suggested the bio-based film could also serve industries such as food packaging, where biodegradable solar cells might power sensors in sterile conditions.
See all the latest news from Greece and the world at Greekreporter.com. Contact our newsroom to report an update or send your story, photos and videos. Follow GR on Google News and subscribe here to our daily email!
