Students representing 17 universities from around world began a 10-day competition in Madrid Friday to design and build the best house run only by solar energy.
The Solar Decathlon Europe (SDE) competition, which brought together student architects and engineers, will conclude on June 27 with the jury naming three winners.
"The competition is called Solar Decathlon Europe as (the competitors) must pass 10 tests as in the Olympic decathlon event," said SDE director Javier Serra Maria-Tome.
The jury, made up of experts in architecture and solar systems, must decide which are the best of the 17 houses based on criteria such as "the best architecture, exterior and interior" or "the best integration of technological components in the architecture," he said.
The teams have each received 100,000 euros (123,000 dollars) from the Spanish housing ministry, but they are also permitted to use additional funds.
Solar Decathlon Europe is taking place in Europe for the first time.
It is organised by the US Department of Energy and was staged in the United States in 2002, 2005, 2007 and 2009.
In Madrid, there are five teams from Spain, two from Germany, two from France, two from the US, two from China, one British and one Finnish.
The "solar village" where the 17 houses will be on show, is next to Madrid Royal Palace and will be open to the public.
Explore further: Salt water quirk key to bubble desalination