UNIVERSITY OF CALIFORNIA, MERCED A hybrid (CSP/CPV) spectrum splitting solar collector for power generation A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Environmental Systems (E.S.) by Bennett K. Widyolar Committee: Professor Gerardo Diaz, Chair Professor Elliot Campbell Professor Yanbao Ma Professor Roland Winston Spring 2018 A hybrid (CSP/CPV) spectrum splitting solar collector for power generation Copyright 2018 by Bennett K. Widyolar The dissertation of Bennett K. Widyolar, titled “A hybrid (CSP/CPV) spectrum splitting solar collector for power generation,” is approved: Chair Date Gerardo Diaz Date Yanbao Ma Date Elliot Campbell Date Roland Winston University of California, MERCED iii Contents Abstract ...................................................................................................................................................... viii Curriculum Vita ........................................................................................................................................... ix Acknowledgements ....................................................................................................................................... x List of Symbols ............................................................................................................................................ xi List of Figures ............................................................................................................................................ xiii List of Tables ................................................................................................................................................ 1 1. Introduction ........................................................................................................................................... 2 1.1 Motivation ........................................................................................................................................... 2 1.1.1 Dissertation Outline ..................................................................................................................... 4 1.2 The Solar Resource ............................................................................................................................. 5 1.2.1 Sun-Earth Geometry .................................................................................................................... 5 1.2.2 Solar Spectrum ............................................................................................................................. 6 1.2.3 Potential ....................................................................................................................................... 7 1.3 Solar Collectors ................................................................................................................................... 8 1.3.1 Concentration ............................................................................................................................... 8 1.3.2 Thermal Collectors ..................................................................................................................... 10 1.3.3 Photovoltaics .............................................................................................................................. 12 1.4 Solar to Electric Conversion (Literature Review) ............................................................................. 15 1.4.1 Concentrating Solar Power (CSP) .............................................................................................. 15 1.4.2 Photovoltaics (PV) ..................................................................................................................... 16 1.4.3 Hybrid (CSP/CPV) Spectral Beam Splitting (SBS) Systems..................................................... 18 2. Spectrum Splitting in Parabolic Troughs ............................................................................................ 21 2.1 Optics of Parabolic Trough Systems ................................................................................................. 21 2.1.1 Single Stage ............................................................................................................................... 21 2.1.2 Two-Stage .................................................................................................................................. 22 2.2 Modelling Approach ......................................................................................................................... 23 2.1.1 Primary Optics and Spectrum Splitting...................................................................................... 24 2.1.1 CPV Subsystem ......................................................................................................................... 24 2.1.2 CSP Subsystem .......................................................................................................................... 25 2.1.4 Combined Performance .............................................................................................................. 25 2.1.5 Parameters, Constants, and Optimization .................................................................................. 26 2.3 Simulation Results ............................................................................................................................ 27 iv 2.2.1 Pure CSP Troughs ...................................................................................................................... 27 2.2.2 Ideal Optical Filters .................................................................................................................... 28 2.2.3 Typical Interference Filters ........................................................................................................ 29 2.2.4 Integrated Solar Cell Filters ....................................................................................................... 30 2.4 Discussion ......................................................................................................................................... 32 2.5 Economics ......................................................................................................................................... 34 2.6 Summary ........................................................................................................................................... 37 3. Generation 1 Prototype Development & Testing ................................................................................ 38 3.1 Collector Design ............................................................................................................................... 38 3.1.1 Two-Stage Optical Design ......................................................................................................... 39 3.1.2 Hybrid Receiver Design ............................................................................................................. 40 3.2 Performance Modelling .................................................................................................................... 42 3.2.1 Optical Model ............................................................................................................................ 42 3.2.2 CPV Subsystem Model .............................................................................................................. 45 3.2.3 CSP Subsystem Model ............................................................................................................... 45 3.2.4 Combined System Performance ................................................................................................. 48 3.3 Prototype Development .................................................................................................................... 49 3.3.1 Primary Mirror ........................................................................................................................... 49 3.3.2 GaAs Cells ................................................................................................................................. 50 3.3.3 Thermal Absorber ...................................................................................................................... 51 3.3.4 Minichannels .............................................................................................................................. 51 3.3.5 Involute Reflectors ..................................................................................................................... 51 3.3.6 Glass Tube ................................................................................................................................. 52 3.3.7 Hybrid HCE Assembly .............................................................................................................. 52 3.4 Experimental Tests ............................................................................................................................ 54 3.4.1 High Temperature Loop Design and Fabrication ....................................................................... 54 3.4.2 Experimental Test Platform ....................................................................................................... 56 Normal Incidence Pyrheliometer ............................................................................................................ 57 3.4.3 Test Results ...............................................................................................................................