A team led by researchers from the University of Michigan (U-M) (Ann Arbor, Michigan) has developed an inexpensive, clear coating that reduced snow and ice accumulation on solar panels, enabling them to generate up to 85% more energy in early testing. Such an advance could dramatically improve the productivity of solar panels in cold climates, as was recently demonstrated in a snow/ice accumulation test in Alaska.
Made chiefly of polyvinyl chloride (PVC) or polydimethylsiloxane (PDMS) plastic, along with silicon or vegetable-based oils, this coating can be sprayed or brush-applied in cold weather and, in its current iteration, can keep shedding snow and ice for up to a year.
“Renewable energy is really taking off right now, but snow is a huge problem in northern climates,” says Anish Tuteja, U-M professor of materials science and engineering. “Solar panels might lose 80 or 90% of their generating capacity in the winter. So figuring out a way for them to continue generating energy throughout the year was an exciting challenge.”
While Tuteja’s lab has developed a number of effective ice-shielding coatings in the past, it was a challenge to design a coating that can passively shed both snow and ice.
“Ice is relatively dense and heavy, and our previous coatings used its own weight against it,” Tuteja says. “But snow can be 10 times less dense than ice, so we weren’t at all certain that the tricks we use on ice would translate to snow.”
With those concerns in mind, Tuteja and his team turned to two key properties that have powered ice-shedding coatings in the past: low interfacial toughness and low adhesion strength (i.e., slipperiness). The latter works well on small areas but tends to lose effectiveness in larger surfaces where more force is needed to slide snow and ice off of it. Therefore, the addition of low interfacial toughness is needed to create cracks so that ice and snow can break free.
The team worked to strike the right balance between the two properties, starting with very rigid PVC plastic for low interfacial toughness mixed with a small amount of vegetable oil for low surface adhesion. They also devised a second material that works equally well using PDMS plastic and silicon-based oil.
U-M researchers collaborated with the University of Alaska (Fairbanks, Alaska, USA) to test the material on a solar field in Fairbanks. After applying the coatings to a subset of panels and monitoring them for a period of about two weeks, the tests showed that the coated panels had an average snow and ice coverage of approximately 28% over an entire winter season, as compared to about 59% for the uncoated panels.
The coating was developed as part of a project led by Sandia National Laboratories (Albuquerque, New Mexico, USA) with funding provided by the Department of Energy’s (DOE’s) Solar Energy Technologies Office.
“As the cost of solar energy has dropped and profitability has climbed, much of the growth in solar energy in recent years has been in northern states, where snow is common,” says Laurie Burnham, the project’s principal investigator. “Snow-phobic coatings, if we can demonstrate their long-term efficacy, will make solar power more reliable and more affordable in snowy regions, helping accelerate our nation’s transition to a more solar-dominated energy economy.”
According to Tuteja, while the current iteration of the coating could be used immediately, the team plans to tweak it further with the aim of developing a coating that can last at least five years.
The study, in collaboration with Sandia National Laboratories and the University of Alaska, was published in Advanced Materials Technologies. A brief video of the Alaska test demonstration can be seen below.
Source: Michigan News, https://news.umich.edu.