Recent Space PV Concentrator Advances: More Robust, Lighter, and Easier to Track Mark O’Neill 1 , A.J. McDanal 1 , Henry Brandhorst 2 , Kevin Schmid 3 , Peter LaCorte 3 , Michael Piszczor 4 , Matt Myers 4 1 Mark O’Neill, LLC, Keller, TX 76248, 2 Carbon-Free Energy, LLC, Auburn, AL 36830, 3 Deployable Space Systems, Inc., Goleta, CA 93117, 4 NASA Glenn Research Center, Cleveland, OH 44135 Abstract — Over the past three years, the authors have collaborated on several significant advances in space photovoltaic concentrator technology, including a far more robust Fresnel lens for sunlight concentration, improved color-mixing features for the lens to minimize chromatic aberration losses for next-generation 4-junction and 6-junction IMM cells, a new approach to sun- tracking requiring only one axis of rotation even in the presence of large beta angles (e.g., ± 50°), a new waste heat radiator made of graphene, with 80-90% reduction in mass, and a new platform for deployment and support on orbit (SOLAROSA). These patent-pending advances are described in this paper. Index Terms — concentrator, Fresnel lens, graphene, inverted metamorphic (IMM) cells, Solar Optical Lens Architecture on Roll-Out Solar Array (SOLAROSA). I. INTRODUCTION AND BACKGROUND Refractive concentrators for space power have been flown successfully for more than 20 years, as shown in Fig. 1. Point-focus versions include the mini-dome lens flight test on PASP+ in 1994-95 [1]. Line-focus versions include the award-winning SCARLET array on Deep Space 1 in 1998- 2001 [2]. The stretched lens array (SLA) built upon the success of SCARLET with a much lighter array, compatible with either a rigid-panel array architecture or a flexible-blanket array architecture [3]. An SLA flight experiment (Stretched Lens Array Technology Experiment, SLATE) flew on TacSat 4 in 2011-2012, achieving excellent performance until a mechanical failure of the lens due to radiation-induced embrittlement of the monolithic silicone material. The lens began to tear in the 7 th month and tore all the way across in the 13 th month of the mission [4]. Since that lens failure, our team has worked on a number of more robust lens approaches to replace the weak monolithic silicone lens construction. The refractive concentrators shown in Fig. 1 all required full two-axis sun tracking for proper focusing on orbit. This limita- Fig. 1. Refractive Concentrators for Space Power – A Long Heritage of Success with 1 Glitch. https://ntrs.nasa.gov/search.jsp?R=20160005277 2020-07-07T00:53:16+00:00Z