China opened a 1-km section solar expressway for testing.
Solar panels are laid beneath part of a ring road surrounding Jinan, capital city of Shandong Province in east China. The road surface is made of a transparent, weight-bearing material that allows sunlight to penetrate.
The panels, covering 5,875 square meters, can generate 1 million kwh of power in a year, enough to meet the everyday demand of around 800 households, according to Qilu Transportation Development Group, the project developer.
"The project will save the space for building solar farms and shorten the transmission distance," said Xu Chunfu, the group's chairman.
Electricity produced by the test section will be used to power highway lights, signboards, surveillance cameras, tunnel and toll gate facilities. Surplus power will be supplied to the state grid, Xu said.
Future functions to be developed include mobile charging for electric vehicles and providing internet connection.
The road has a designed life of 20 years. It has three layers -- a concrete layer pervious to light on top; thin amorphous silicon panels in the middle; a waterproof insulate protection layer at the bottom.
"The top layer has good flexibility which can both withstand the pressure of large vehicles and protect the fragile amorphous silicon boards underneath," said Zhang Hongchao, chief scientist with Shandong Pavenergy company which was involved in the development of the project.
Xu did not reveal the cost but said it was half of similar projects in foreign countries.
"With the development of solar power in China, the cost can be further reduced," he said.
China leads the world in solar power development. Its annual increase of new installed generation capacity has been the largest in the world since 2013. As of the end of September, China's installed photovoltaic capacity hit 120 gigawatts.