Andrew Gellman, a Lord Professor of Chemical Engineering at Carnegie Mellon University, explains how photovoltaic cells function to generate solar electric power.

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Transcript

How is solar electric power generated and captured?

HOST:  Have you ever wondered how energy is generated from sunlight? On this week’s Energy Bite, Andy Gellman, a professor at Carnegie Mellon University, has some answers.

ANDREW:  Solar electric power is generated by materials called photovoltaics. When sunlight hits a thin wafer of silicon, a photovoltaic, the solar energy separates positive and negative charges near the surface so that the silicon wafer behaves like a battery. The photovoltaics cause the negatively charged electrons to go to one side of the wafer, which becomes the negative terminal of the battery. The positive charges go to the other side, which becomes the positive terminal.

HOST:  How does using the different materials used as photovoltaics influence their ability to convert sunlight to energy?

ANDREW:  The light from the sun has a spectrum of colors that we see in the rainbow; red through yellow to purple, and colors like infrared that we cannot see. Photovoltaic materials can only absorb light colors over a specific range. Those materials that absorb over a wide range of colors collect a greater fraction of the solar energy than those absorbing over a narrow range of colors. Ongoing research efforts aim to maximize the efficiency of solar energy conversion to electricity while also reducing the costs of solar cells.

HOST:  Do you think the nation’s investment in solar energy research should be increased? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.