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  1. 1. Integration of Triple Junction Solar Panels in Nanosatellite Power Systems Ali Alqaraghuli, John L. Crassidis, PhD. Department of Mechanical and Aerospace Engineering, University at Buffalo Introduction Space Debris: There are various bits of rock and dust in space, originated mostly from comets. In the 21st century, most of the space debris is a result of satellite wreckage due to failure in mission or collision with another satellite. There are also nonfunctional satellites floating in orbit. Broader Impact: To prevent satellites from colliding in the future, and protect existing satellites from space debris, the University at Buffalo Nanosatellite Laboratory in partnership with the Air Force Research Laboratory have released two sister missions: •  Glint Analyzing Data Observation Satellite (GLADOS) •  Spectrometry Observation for Reflectivity Analysis (SORA) The data collecting device for GLADOS will be two visible and near IR Cameras, while SORA uses a spectrometer. The GLADOS prototype is shown below: Structure:   GLADOS is a shoe-box- sized satellite, the two cameras are also shown in the picture. These cameras record and gather data from the light reflecting off space debris, also known as glint testing Dr. Crassidis’ ‘Glint theory”. Figure  2:  GLADOS  Design   Hypothesis Triple-Junction Solar Panels provide a broader range of accepted wavelengths due to the three layers, and therefore have the ability to support a more efficient recharging system for lithium ion battery in Nanosatellite power system. Project Objectives Triple-Junction Solar Panels will be used for the following reasons: •  Multiple junctions allow for a broader wavelength tolerance, therefore more of the sunrays can be used to transfer solar radiation into electrical current. •  Use of three different semiconducting materials allows three different p-n junctions, which allows cell to be more efficient. •  Theoretically, infinite junction solar panels have a theoretical efficiency of around 84%, vs. a maximum theoretical of 34% for single junction solar panels. Visible light can be broken into a large array of wavelengths represented by a different color. In a theoretical infinite junction solar cell, all wavelength ranges would transform solar radiation into electrical current. Breakdown of the Solar Cells •  26.8% Efficiency •  Up to 31 cm2 size •  Integral Bypass Diode Protection •  Transparent Insertion into Existing Systems •  Varying extreme environmental tolerance •  Three semiconductor layers, as each layer is populated with holes of varying sizes to suite the varying wavelengths Research Methods Results and Conclusion It was found that two of the three layers are activated by infrared wavelengths, rather than visible light. The following values are the spike wavelengths for each one of the semiconductor layers: A. AlInGAP: 520 nm wavelength B. GaAs: 740 nm wavelength C. InGaAs: 940 nm wavelength Figure 10, 11, 12: LED power and wavelength ranges Acknowledgements John L. Crassidis, Ph.D., Dept. of Mechanical and Aerospace Eng. Mara Boardman, Chief Engineer, UB Nanosatellite Laboratory Rohan Kuriakose, Jiazhe Chen, Dept. of Electrical Engineering The Collegiate Science and Technology Entry Program (CSTEP) References Throughout the electronic age, space vehicles have shaped our modern civilization and created a more connected world. Satellites are now designed to perform serious duties while hosting smaller structures. However, with smaller satellites, smaller solar cells need to be implemented, which can cause a dilemma in the case of recharging the vehicle’s battery. For a cell to maintain high efficiency at a small size, it must have multiple junctions. For the purposes of the University at Buffalo Nanosatellite Laboratories’ (UBNL) Space Debris sister satellites, triple junction solar cells can provide reliable and renewable power to small satellites to guarantee data and command handling, in addition to recovering power lost to tumbling. Figure 1: Glados Integration Abstract Solar Panels:   GLADOS will be powered using the solar panels integrated by UBNL, they are formed of triple- junction solar cells, which will be responsible for recharging of Lithium Polymer battery, This battery was chosen based on the space environment. Figure 3: Newtonian Visible Light Prism Figure 4:ITJ Solar Cell Figure 5: Cell Material Before the integration of the solar panels onto the satellite, three tests must be performed: 1.  Spectroscopy Test: Before launching the solar panels into space, they must be tested on ground to verify whether they can tolerate the given wavelength ranges in the sheet. It is important to activate all three junctions at the same time, or else leakage current can end up harming the cells which would cause the entire satellite power system to fail. This can be done easily using an array of LEDs. A schematic and an assembly of LED arrays is visualized below. 2. Environmental Chamber Test: Following testing the full activation of three layers, the cells must be tested for surviving the conditions through the atmosphere and outer space, meaning extremely hot and cold temperatures. This is done using an environmental chamber similar to the one shown below. Figure 6: LED Array Design via Diptrace Software Figure 7: Printed Circuit Board Figure 8: Uniform LED Array Figure 9: SE-300 SE-300 Thermal Chamber:   MOOG is responsible for performing the Environmental Chamber Test. The panels would go into the chamber and use a prototype for structural support. The LED array designed above would be facing the screen from the outside. This is due to the LEDs intolerance of the heating range for the chamber, as well as the change in light emission for the LEDs that take place with changes in temperature. Guter, Wolfgang, et al. "Current-matched triple-junction solar cell reaching 41.1% conversion efficiency under concentrated sunlight." Applied Physics Letters 94.22 (2009): 223504. SpectroLab, a Boeing company, for providing most of the graphs in solar cell datasheet.