Japan developed a pavement system that generates electricity by using sunlight.
Nippo Corp and Mirai-Labo Co Ltd (Hachioji City, Tokyo) co-developed a pavement system that generates electricity by using sunlight.
They constructed the power-generating pavement system on a trial basis on the premises of Nippo General Technology Center. And the company checked the durability and power-generation efficiency of the system.
According to Nippo, this is the first time that a pavement having a solar power generation (PV) function has been developed in Japan. The company aims to commercialize the pavement system by 2022.
Photo: The PV module was installed on the premises of Nippo General Technology Center in Saitama City.
Nippo and Mirai-Labo developed a PV module consisting of film-like solar cells, wiring and transparent plastic plate that protects the surface. It is installed by (1) applying resin mortar (as adhesive) to an existing asphalt pavement to control irregularities and (2) attaching the PV module on it.
Electricity generated with the system is transferred to a dedicated power storage system, and it can be sent to street lamps around the pavement. The power storage system is equipped with multiple compact, detachable batteries. At the time of disaster, the batteries can be carried to shelters and medical facilities and used as emergency power sources.
Nippo had been engaged in the development of the pavement that generates electricity by using sunlight since 2017.
“We considered whether it is possible to add a new function, namely a power source, to a road that had been prioritizing the realization of space in which people and vehicles can safely move,” the company said.
Nippo focused on PV pavements that were in the stage of verification in France, the Netherlands, etc. And they started the development by using materials that can be procured in Japan.
Film-like battery that does not break even when large-size vehicle runs on it
Durability was the problem of the pavement system. General PV modules to be installed on roofs, etc often use solar cells made by embedding, for example, crystal-based power-generating devices in reinforced glass plates.
While such solar cells have a high power generation efficiency, they are vulnerable to deformation such as deflection. So, if they are introduced to pavements to which heavy loads are applied, they can be broken soon.
On the other hand, the film-like solar cell developed by Mirai-Labo is flexible enough to be bent by human hands. It is combined with a high-strength plastic plate to realize a structure resistant to deflection.
Its durability was confirmed in a test with a wheel load of 5t on the assumption that a large-size vehicle runs on the pavement. During the test, Nippo confirmed that the power generation function was not affected by the load.
Fine irregularities were formed on the surface of the plastic plate for preventing slipping. Nippo has already confirmed that the surface of the plastic is not scraped even when a vehicle having tires equipped with chains repeatedly runs on the pavement in winter and that it is possible to keep the skid resistance.
Furthermore, the company found that the irregularities on the surface makes it easier to receive diagonal sunlight, improving power generation efficiency.