Competitors from around the world face off in the Department of Energy’s Solar Decathlon. The contest was started to demonstrate that solar power can be practical and affordable. This year’s event is held in West Potomac Park, a move from its usual home on the National Mall.
A built-in dining table, made of concrete to help hold heat from sunlight, inside the New Zealand entry in the Solar Decathlon. Bill O'Leary/The Washington Post Buy Photo