Shandong police are investigating damage to the world's first solar expressway in Jinan, Beijing Youth Daily reported on Friday.

A protective layer of a solar panel, measuring about 1.85 meters long and about 10-15 centimeters wide, was found to be missing during a routine check. Another seven photovoltaic road assemblies also appeared to have been tampered with.

The damage occurred just five days after the expressway was officially opened.

The solar road surface consists of a transparent, weight-bearing material that allows sunlight to penetrate.

Each panel consists of three layers. The bottom layer is moisture preventing insulation, the second consists of the photovoltaic devices and the third is a protective layer made of transparent concrete.

The 1,120-meter-long section, covering 5,875 square meters, can generate 1 million kwh of power in a year, enough to meet the demand of about 800 households, according to Qilu Transportation Development Group, the project developer.

"The preliminary repair work has been completed and the road has resumed operation," a member of staff from the Qilu Transportation Development Group was quoted as saying by the newspaper.

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