This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE JOURNAL OF PHOTOVOLTAICS 1 Mitigation of Dust Impact on Solar Collectors by Water-Free Cleaning With Transparent Electrodynamic Films: Progress and Challenges Malay K. Mazumder, Life Fellow, IEEE, Mark N. Horenstein, Life Fellow, IEEE, Nitin R. Joglekar, Member, IEEE, Arash Sayyah, Jeremy W. Stark, Annie A. R. Bernard, Sean M. Garner, Julius E. Yellowhair, Hung Yi Lin, Ryan S. Eriksen, Alecia C. Griffin, Yujie Gao, Ricci La Centra, and Alexis H. Lloyd Abstract—Energy-yield loss caused by soiling of photovoltaic modules and concentrated solar power (CSP) mirrors in utility- scale power plants installed in semiarid lands and deserts would result in unsustainable demands for fresh water needed for clean- ing. This paper reviews the progress of the electrodynamic screen (EDS) film technology for frequent water-free cleaning with low- energy requirements. Results presented here, based on laboratory- scale EDS-film-laminated solar panel cleaning, show that the output power can be restored higher than 95% of the initial power under clean conditions. For solar mirrors, the specular reflection efficiency can be maintained over 90% ensuring high efficiency of the CSP plants. Operation of the EDS film for main- taining high optical efficiency of solar collectors requires less than 0.2 Wh/m 2 /cleaning cycle. Principles, optical modeling, construc- tion, lamination of the EDS films on modules and mirrors, and experimental data showing optical efficiency restoration without water consumption are presented. Current challenges in develop- ing electrodes that would meet optical and conduction properties, Manuscript received December 16, 2016; revised May 26, 2017; accepted June 22, 2017. This work was supported by the Department of Energy (DOE CSP APOLLO EE-0007119) through research project on “Enhancement of Optical Efficiency of CSP Mirrors for Reducing O&M Cost via Near-Continuous Operation of Self-Cleaning Electrodynamic Screens” and cost-sharing grants from Massachusetts Clean Energy Center and EDS Chile SpA. (Corresponding author: Malay K. Mazumder.) M. K. Mazumder, M. N. Horenstein, A. A. R. Bernard, R. S. Eriksen, and A. C. Griffin are with the Department of Electrical and Computer Engineer- ing, Boston University, Boston, MA 02215 USA (e-mail: mazumder@bu.edu; mnh@bu.edu; annieber@bu.edu; reriksen@bu.edu; aleciag@bu.edu). N. R. Joglekar is with the Questrom School of Business, Boston University, Boston, MA 02215 USA (e-mail: joglekar@bu.edu). A. Sayyah was with the Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 USA. He is now with the Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 USA (e-mail: arashs@mit.edu). J. W. Stark was with the Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 USA. He is now with MagCanica, San Diego, CA 92117 USA (e-mail: jwstark@bu.edu). Y. Gao, R. La Centra, and A. H. Lloyd are with the Division of Materials Science and Engineering, Boston University, Brookline, MA 02446 USA (e- mail: yujiefly@bu.edu; lacentra@bu.edu; ahlloyd@bu.edu). S. M. Garner is with the Corning Research and Development Corporation, Corning, NY 14831 USA (e-mail: garnersm@corning.com). J. E. Yellowhair is with the Concentrating Solar Technologies Depart- ment, Sandia National Laboratories, Albuquerque, NM 87185 USA (e-mail: jeyello@sandia.gov). H. Y. Lin is with the Industrial Technology Research Institute, Hsinchu 31040, Taiwan (e-mail: hylin@itri.org.tw). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JPHOTOV.2017.2721462 low-cost production, and meeting long-term outdoor durability of the EDS films are discussed. Index Terms—Cleaning, dust impacts, electrodynamic screen (EDS), flexible glass, optical efficiency, solar collectors. I. INTRODUCTION H OT deserts and semiarid areas cover more than one-fourth of the Earth’s total landmass; these vast areas receive the highest solar irradiance and least interruptions from cloud and rain. Utility-scale solar plants are mostly installed in semiarid and desert lands and are subjected to high dust deposition rate. Dust layer build-up on solar collectors causes a major energy- yield loss [1]–[5]. For high optical efficiency of solar collectors such as photovoltaic (PV) modules and concentrating mirrors, the optical surface must be kept clean against dust deposition that reduces the efficiency of light transmission. To maintain optical efficiency of solar collectors close to its initial value under clean condition, frequent cleaning is needed at intervals depending upon the rate of dust deposition at the plant site. Washing solar collectors with water and detergent is the most commonly practiced method for cleaning [6]–[9]. The conven- tional approach for cleaning collectors in utility-scale plants is to use a large truck with a water tank and a pump system for spraying deionized water. Robotic brush cleaning is also used for smaller solar plants, which uses less water and detergent [10]–[13]. However, manual or robotic cleaning with water is often a critical problem in areas where water is scarce and con- servation of water is needed. In addition, these methods are both labor and energy intensive and are interruptive to routine plant operations. If the global solar power output is to increase to hun- dreds of gigawatt levels, as is envisioned, efficient operation of solar plants would result in an unsustainable demand for fresh water. Unless a water-free or a low-water cleaning method is es- tablished, continued growth in global utilization of solar power plants may lose public support in areas suffering long intervals of drought. One of the promising low-water-based cleaning processes is to apply a transparent superhydrophobic (SH) coating with nanostructured surface on the optical collectors for reducing adhesion of dust particles to improve cleaning efficiency with 2156-3381 © 2017 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications standards/publications/rights/index.html for more information.