Every two years, international teams fight it out using computer models and engineering expertise at the Solar Decathlon, a kind of Olympics for solar-powered homes. Teams of students design, build and operate houses that are powered only by solar energy. The homes open to the public.

The teams work for two years to develop ways to reduce the cost of solar-powered homes and advance solar technology in general. This year’s competition is special since the US Department of Energy will provide $100,000 (US) to each participating team.