Graduate Seminar Series

A Brief (but Amazing!) History of how Photovoltaics Became the Dominant New Electric Power Source in the US

World use of photovoltaic (PV) solar electricity has been increasing at an average annual exponential growth rate, 35% since about 2000. Not surprisingly, during this same time, the percentage of US-consumed energy (~100 Quadrillion BTUs total) derived from PV has increased from ~0.001% in 2004, to ~1% at the end of 2018. Indeed, if these trends continue, PV could produce ~25% of all energy consumed in the US by as early as 2030. Combining this with the rapidly decreasing energy costs for large grid-tied PV systems (presently <2.5¢/kWh for long-term power purchase agreements) largely explains why PV-derived energy is – even now – a main source of new US and world electric energy. Although the majority of this PV-derived energy is presently generated by crystalline-based Si module technologies, because of combined efficiency, production, cost, and other advantages, an ever-increasing amount of PV energy is being produced from polycrystalline thin-film (TF) materials. These TF PV technologies owe much of their rapidly advancing success to improved understanding in related materials synthesis, while applying these advancements to industry, in turn, has relied on design innovations of related vacuum-process equipment. This talk will briefly overview the present state of TF PV technologies, taking into consideration both the present dominance of crystalline Si PV, and evolving trends in TF PV. Several examples where keen understanding of vacuum processes in laboratory-scale devices has fostered successful utilization of advanced vacuum technology in the commercial TF PV industry will be presented. The talk will also suggest some areas where further advancements in vacuum-process and equipment innovation could yield potentially even lower-cost TF PV technologies.

Tim Gessert, 2022 AVS President, Gessert Consulting, LLC

Timothy Gessert is the Principal Scientist and Managing Member of Gessert Consulting, LLC (Conifer, Colorado, USA), and a former/retired Principal Scientist at the National Renewable Energy Laboratory.  Tim received undergraduate degrees in Physics and Mathematics from University of Wisconsin River Falls in 1982, M.Sc. in Physics from Colorado School of Mines in 1984, and Ph.D. in Applied Physics from University of Wales - College of Cardiff in 1996.  His 40+ years of research have included synthesis and characterization for photovoltaic and other materials including GaAs, InP, Si, CuInGaSe₂, CdTe, and transparent conducting oxides (TCOs).  Major interests have also included training and mentoring of undergraduate and graduate students, and is presently or previously an adjunct faculty member at Colorado School of Mines, Colorado State University, University of Toledo, Vanderbilt University, and University of Illinois at Chicago.  Tim has collaboratively published over 230 papers, 1 book, 6 book chapters, and has over 30 awarded or pending U.S. patents.  He is active in developing and teaching both in-person and virtual short courses and in developing related web content for institutions and societies involved in Vacuum Technology, Contamination Control, Transparent Conducting Oxides, and Thin-Film Photovoltaics.  Tim has been a long-term member of the American Vacuum Society (AVS, serving currently as President of the Society in 2022), the Society of Vacuum Coaters (SVC), the Materials Research Society (MRS), the Institute of Electrical and Electronic Engineers (IEEE), and the Institute of Physics (IOP).  He has served on numerous Conference Committees and Editorial Boards, and is presently the Editor-in-Chief of the technical journal Thin Solid Films.