Secretary Panetta holds slate of solar cells Secretary of Defense Leon E. Panetta holds slate of solar cells as he listens to a Marine officer describe the energy efficiency efforts of the U.S. Marine Corps at the Pentagon's Energy Security Event on Oct. 4, 2012. SHARE IMAGE: Download Image: Full Size (0.07 MB) Photo By: VIRIN: 406615-I-XIK41-195.jpg Photo Gallery