| Work Detail |
Chinese scientists have proposed using soda-glass-doped polydimethylsiloxane films to reduce the temperature of solar modules. The coating achieved a solar transmittance of 94.8% and a sky window emissivity of 95.3%.
A group of researchers from Chinas Shandong University and Xian Jiaotong University have developed a radiative cooling cover for photovoltaic panels that can reduce their operating temperature by up to 3.72%.
Radiative cooling occurs when the surface of an object absorbs less radiation from the atmosphere and emits more. As a result, the surface loses heat and a cooling effect can be achieved without the need for energy.
“Our study is based on numerical simulations, the reliability of which has been ensured by cross-validations with existing studies including experimental results,” Dr. Maoquan Huang, author of the study, explains to pv magazine . “We are also planning experiments to test prototypes of RC covers on PV panels under different meteorological and environmental conditions.”
The new coating is made of polydimethylsiloxane (PDMS) films doped with soda glass (PDMS-SG) and is intended to replace conventional glass coatings. “Based on previous studies, this study presents a transparent RC coating with a randomly doped particle structure on a PDMS substrate,” the researchers say. “The study further explores the efficiency and potential of RC-PV systems in China’s diverse meteorology using hourly meteorological data.”
Using numerical analysis, the group compared several doping materials, including titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), soda ash glass, silicon dioxide (SiO2), polyvinyl chloride (PVC) and polystyrene (PS). “Soda ash glass proved to be the best choice, offering an optimal combination of solar transmittance and long-wave infrared (LWIR) emissivity,” the researchers explain.
Following this analysis, and also using numerical studies, the group calculated the structural parameters of PDMS-SG that would give the best radiative results. They found the ideal results when the PDMS-SG film was simulated with a particle diameter of 4 µm, a volume fraction of 1.5%, and a film thickness of 100 µm. The result was a solar transmittance of 94.8% and a sky window emissivity of 95.3%, which translated into a peak power of 147.6 W/m2.
After optimizing the design, the group simulated its performance in different regions of China. To do this, the cell was assumed to be a 200 µm thick crystalline Si layer placed on an aluminum (Al) catadioptric. It was compared to a reference cell with a 5 mm thick silica glass cover in the different regions of China.
“In order to understand the application potential of RC-PV systems in China, we have delineated four distinct zones based on the annual efficiency increase rates ??,” the group explains. “These zones are named: optimal application zone (?? = 3.50%), high potential zone (3.26% = ?? < 3.50%), moderate potential zone (3.02% = ?? < 3.26%) and limited potential zone (2.78% = ?? < 3.02%).”
According to their findings, the novel CR was able to increase the annual electricity output by 2.78% to 3.72%. The optimal application area was found to be Tibet, as it benefits from a severe cold climate zone, the most abundant solar radiation and clear skies. Provinces such as Xinjiang are in the high potential zone, while Inner Mongolia is in the moderate potential zone. Provinces such as Hunan and Sichuan were in the limited potential zone in this research.
“The performance of RC-PV systems decreased from west to east in China, with the largest increase in regions characterized by dry and cool climates and predominantly sunny days,” the academics concluded. “These results demonstrated the advantages of RC-PV roofs under real-world meteorological and environmental conditions. This study contributes to the application of RC films to photovoltaic systems and provides valuable insights into the utilization of solar energy in future energy infrastructure.”
Their findings were presented in “ The potential of radiative cooling enhanced photovoltaic systems in China ,” published in Advances in Applied Energy . |
