Design, Build, and Testing of TacSat Thin Film Solar Arrays

MicroSat Systems, Inc. (MSI) has developed a low cost, lightweight, solar array system using thin-film photovoltaic (TFPV) material to meet power generation needs for future responsive space missions. The Fold Integrated Thin Film Stiffener (FITS) is the deployment portion of the system. FITS is an integrated, passively deployed solar array structure designed specifically for TFPV, however a variety of photovoltaic (PV) options can be utilized by using the FITS deployment technology. FITS extends the boundaries of space PV systems by eliminating conventional rigid structures and mechanisms to maximize the lightweight and low stowage volume advantages of TFPV. FITS uses multifunctional, foldable components that store energy to provide deployment force and deployed stiffness, and have integrated power cabling to meet the demanding mass, cost and power requirements of programs like the TacSat series and anticipated future responsive space missions. MSI has completed the build and qualification test program for a two wing experimental solar array for the Air Force Research Laboratory (AFRL) TacSat-2 mission scheduled for launch in November of 2006. The array utilizes amorphous silicon (a-Si) thinfilm photovoltaics on a 1-mil stainless steel substrate from United Solar Ovonic (USOC), integrated with MSI’s patented FITS solar array deployment system. The experimental solar array will provide 120 W of additional power to the spacecraft on top of the primary solar arrays while providing valuable on-orbit performance data of the TFPV to the aerospace community for future mission planning. This characterization will be done by monitoring current, voltage, and temperature of the array wings over time using an I-V electronics box built by Lockheed Martin in Littleton, CO. Currently, MSI is under contract with AFRL to design, fabricate, and test a 380 W EOL FITS wing while focusing on the scalability and modularity of the FITS design. For the current program, MSI is designing a FITS wing consisting of four modular strings using USOC a-Si TFPV material on polymer substrate of approximately 95 W EOL each. This wing design will result in a 2 wing FITS solar array of 760 W EOL, however, because of the module array design, another string could easily be added to each wing resulting in a 950 W EOL array. This paper will discuss the current status of the design, build, and test of the TacSat-2 experimental FITS solar arrays and how the lessons learned from that program are being applied to the 380 W EOL FITS solar array design. It will outline the current status of the 380 W EOL FITS solar array as well as the benefits of the FITS solar array technology compared to state of the art conventional rigid arrays.