1. Variation of Solar Absorptance of CNT Coating with Incident Angle Zijuan Lai, Dr. Forrest Schultz University of Wisconsin-Stout, Menomonie, WI 54751 Introduction With the explosive development of science and technology, solar energy, as a form of alternative energy sources, is becoming increasingly important! However, capturing this energy is still a science and engineering challenge that has not yet been solved. At UW-Stout, a carbon nanotube and ceramic nanoparticle based black coating for solar panels has been developed. The goal of this research project is to explore the variation of solar absorptance of UW-Stout coating and commercially available coating at different incident angles by using an integrating sphere attachment with UV-VIS-NIR spectroscopy. Instruments UV-VIS-NIR spectroscopy can use light in the ultraviolet, visible and near infrared ranges to determine the absorbance of liquids. However, using an integrating sphere attachment allows the instrument to measure the percent of light reflected away from a sample. Additionally, an absolute reflectometry attachment is used to change the incident angle. Materials Six samples, including both of UW-Stout coatings and commercially available coatings, have been measured at incident angles of 5 degrees, 12 degrees and direct normal angle. Our experimental data indicates that the UW-Stout coating exhibits variation based on formulation parameters. Measurement and Calculation Eq (1) %A = 1 - %R Eq (2) R s = Σ (E S * %A)/ Σ E S Equation 1 and 2, derived from ASTM G 173-03, are used to calculate the solar absorptance of the samples. A Get the data of sample reflectance with UVProbe software B Calculate the absorptance (%A) of the sample by using Equation 1 C Get the data of solar irradiance (Es) from ASTM G 173-03 Reference D Calculate the solar absorptance (Rs) of the sample by using Equation 2 Conclusion: Our experimental data indicates that the UW-Stout coating exhibits variation based on formulation parameters. 1. Effect of Incident Angle Measure each sample respectively at incident angles of 5 degrees, 12 degrees and direct normal angle, and then we can get all samples’ overlaid spectrum of different angles. Conclusion: Our experimental data indicates that the smaller the incident angles is, the less the sample reflects, the more the sample absorbs. 2. Compare the performance of UW-Stout coating and commercially available coating Generally, the performance of the UW-Stout coating is similar to that of commercially available coatings at incident angles of 5 degrees, 12 degrees and direct normal angle, but a closer look at Figure 2 and Figure 3 shows that the Mirotherm sample surpasses the UW-Stout sample. Figure 3 indicates that the highest solar irradiation occurs between 300nm with 1500 nm and Figure 2 indicates that when scanning between 300nm with 1500nm the reflectance of Mirotherm is lower than that of Sample 6, which performs best during all the UW-Stout samples. Therefore, in order to improve the efficiency of CNT Coatings, we need to increase its solar absorptance in the range where there is much solar irradiation. Discussion For Further Information For more information please contact Zijuan Lai laiz4264@my.uwstout.edu Figure 3.) Solar Radiation Spectrum Figure 1.) Reflectance of Mirotherm at 5 degrees, 10 degrees and normal angle Figure 2.) Reflectance of Mirotherm and Sample 6 at direct normal angle Instrument Settings InstrumentMPC-3100 UV-3600 Measuring ModeReflectance Scan SpeedFast Scan Range (nm)200-2500 Slit Width (nm)32 Sampling Interval (nm) 2 Sample123456 Formati on Aluminu m Mirothe rm CNT Coating NO.53 CNT Coating NO.56 CNT Coating NO.64 CNT Coating NO.82 Sample123456 Solar Absorpt ance 0.1730.7140.6960.6800.6420.705