Engineering news
Researchers in the Netherlands have developed a method for imprinting existing solar panels with silicon nanopatterns that reflect green light back to the observer. This makes them look green from most angles, but only reduces the amount of power absorbed by about 10%.
“Some people say 'why would you make solar cells less efficient?' But we can make solar cells beautiful without losing too much efficiency," said Verena Neder, lead author of the paper and a researcher at AMOLF, which conducted the work. “The new method to change the color of the panels is not only easy to apply but also attractive as an architectural design element and has the potential to widen their use.”
This development could improve the uptake of solar panels, according to Leonie Greene, head of external affairs at the Solar Trade Association. “We have done a lot of work trying to promote the aesthetics of solar panels,” she told Professional Engineering, adding that new colours could invite interest from architects as well as home-owners.
Green panels could be particularly welcome in the countryside, where solar arrays are becoming an increasingly viable option for power-generation. This could allow them to be installed with less visual impact on the environment.
Coloured solar panels are already available, but they use dyes and reflective coatings that tend to greatly reduce their efficiency. Another route, which has been adopted by Tesla, is ‘solar tiles’ made of glass and designed to mimic existing roof tiles. These will be available in the UK in 2018 in a range of four colours.
Neder and her colleagues were able to create a more efficient coating using a technique called soft-imprint lithography, which stamps a dense array of silicon nanocylinders onto the surface of each panel.
Each nanocylinder is about 100 nanometres wide, and can be tuned to scatter a particular wavelength of light depending on its geometry. “In principle, this technique is easily scalable for fabrication technology,” said Albert Polman, a scientific group leader at AMOLF and senior author on the paper. "You can use a rubber stamp the size of a solar panel that in one step, can print the whole panel full of these little, exactly defined nanoparticles.”
Unlike existing coloured solar panels, these ones will look the same colour from any angle. The researchers are now working on creating red and blue solar cells, and once they’ve mastered all three, they’ll be able to create any colour they want. “You have to combine different nanoparticles, and if they get very close to each other they can interact and that will affect the color," Polman said. "Going to white is a really big step.”