Colloquium: J. Roger P. Angel

    Thursday, April 23, 2015 - 3:30pm - 5:00pm
    Meinel 307

    "Focusing Optics for Solar Energy"


    This talk will explore the potential for solar energy to become the main source of electricity worldwide. Today, nearly all solar electricity is made by flat photovoltaic panels. This is a successful and rapidly growing $100 billion industry, but yet accounts for less than 1 percent of global electricity production. Its main present limitations are intermittency and low conversion efficiency.

    Intermittency may be overcome by storing solar energy as heat, for later conversion to electricity by electromechanical means. Present solar thermal storage plants are on a very large scale, concentrating approximately 1,000,000 square meters, and are not very efficient. Angel's group is exploring a new optical configuration that promises higher concentration and temperature (for high Carnot conversion efficiency) at moderate cost, at a unit scale of approximately 1,000 square meters.

    The low 20-percent conversion efficiency of single bandgap photovoltaic cells, such as silicon, to the broad solar spectrum may be overcome by using multijunction photovoltaic cells with 40-percent conversion efficiency. These cells, developed for space solar power, are approximately 100 times more expensive per unit area than silicon photovoltaic panels, but used in 1,000-times focused light become 10 times less expensive per unit of output power. Angel's group is developing inexpensive concentrating optics using large sagged glass mirrors to exploit these cells for lower-cost, higher-efficiency photovoltaic plants.

    Speaker Bio(s): 

    J. Roger P. Angel is a Regents’ Professor of astronomy and optical sciences at the University of Arizona. He is a member of the National Academy of Sciences, a fellow of the Royal Society, a former MacArthur Fellow and the founder and CTO of REhnu. He developed concepts, technology and manufacturing facilities to make the largest and most powerful astronomical telescope mirrors. Today he is working on novel approaches to harvesting solar energy using large, mass-produced, self-supporting glass mirrors.