Researchers from the Hong Kong Polytechnic University (PolyU) have developed a new hydrogel coating for solar panels.
The novel coating, presented in the study “Enhancing Photovoltaic Efficiency and Durability with Advanced Hot-Spot Management,” published in the journal Advanced Energy Materials, is purportedly capable of enhancing the heat dissipation in solar panels in order to cool any hot spots, while also increasing power generation efficiency.
Yan Jerry, Chair Professor of Energy and Buildings at PolyU, told pv magazine the hydrogel coating is mainly made from polyacrylamide (PAM), a water-absorbing gel, bonded together with hydroxyethyl cellulose (HEC). “To make it stronger and more durable, we add HEC, which helps hold the gel together,” he explained. “Leafy-patterned cotton threads are placed inside the gel to help move water to the hottest areas, keeping the cooling effect even.”
The outer layer of the hydrogel is a thin, porous film of polytetrafluoroethylene, also known as Teflon, which Professor Yan explained keeps dust off and controls how quickly the water evaporates.
Applying the hydrogel coating to solar panels lowered hot spot temperatures by up to 16.2 C, according to the team’s research, outperforming conventional hydrogels which can reduce such temperatures by up to 10.7 C. This advancement was found to boost cooling power to 463.8 W m−2, equivalent to a 13% improvement in power output.
Analysis in the research paper indicates that when applied to rooftop and building-integrated photovoltaic (BIPV) systems, the hydrogel coating could mitigate nearly half of the power losses related to hot spots. Using Hong Kong and Singapore as case studies, the researchers calculated potential annual power generation increases of 6.5% and 7.0%, respectively, with estimated payback periods of 4.5 years and 3.2 years.
“Traditional hydrogels can experience volumetric shrinkage of up to 46% after extended use, whereas our innovation significantly reduces cracking and shrinkage, limiting the volumetric shrinkage rate to 34%,” added Liu Junwei, Research Assistant Professor of the Department of Building Environment and Energy Engineering.
Professor Yan told pv magazine the team now plans to continue researching and improving its hydrogel coating, by making it more durable, reducing shrinkage and finding ways to lower production costs.
“The next steps include running large-scale outdoor tests in different climates to see how well the coating works in real-world conditions,” the professor said. “Also working closely with industry partners to improve the manufacturing process, so the coating can be produced on a large scale and brought to the global market.”
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