This article is based on the Fred Kavli Distinguished Lectureship in Nanoscience presentation given by Harry Atwater (California Institute of Technology) on April 5, 2010 at the Materials Research Society Spring Meeting in San Francisco, CA. The Kavli Foundation supports scientific research, honors scientific achievement, and promotes public understanding of scientists and their work. Its particular focuses are astrophysics, nanoscience, and neuroscience.
Solar energy is currently enjoying substantial growth and investment, owing to worldwide sensitivity to energy security and climate change. Solar energy is an inexhaustible resource and is in abundant supply on all continents of the world. The power density of sunlight (~1000 W/m2) and the efficiency of photovoltaic devices (~10–25%) are high enough so that land use does not limit photovoltaic deployment at the terawatt scale. However solar photovoltaics are currently too expensive to achieve parity with other forms of electricity generation based on fossil fuels. This is largely due to the cost (and for some cases, the abundance) of materials used in photovoltaic modules and systems, and the cost of deploying in current form. This economic and social context has created the present situation where there is widespread interest in photovoltaic technology for power generation, but the cumulative installed world capacity for photovoltaics is <50 GW, and it appears to be very challenging for photovoltaics to play a very substantial role in large-scale (terawatt) electricity generation in the short term.