Solar Plant Designed to Minimize Damage to Roof
Spreading across logistics center roof, securing ease of maintenance
Fig. 4: A total of six clasps holding a solar panel on both of its long sides. A solar panel was installed with three clasps on each side on the three tops of the folded-plate roof. (source: Nikkei BP)
Logistics bases with large roofs are being focused on as prospective locations for on-roof-type large-scale solar power generation systems. The mega (large-scale) solar power plant with 2MW output located on the roof of "Hibiki International Logistics Center" in Kitakyushu City, Fukuoka Prefecture, is one such base. On the roof, which has a length of 290m, 8,244 solar panels are mounted (Fig. 1 & 2).
Daiwa House Industry Co Ltd owns and rents Hibiki International Logistics Center to tenant enterprises (Fig. 3). The mega-solar power generation system on the roof was installed by Daiwa House Industry, and its subsidiary Daiwa Energy Co Ltd sells the generated power to Kyushu Electric Power Co Inc as a power producer. Daiwa Energy plans roughly ¥80 million (approx US$780,107) power sales per annum, expecting a total of about ¥1.6 billion in power sales over the 20 years from October 2012, when it started selling electricity.
Daiwa House Industry is Japan's leading house manufacturer dealing not only with houses but also large-scale facilities. Given the nature of its business, the company is highly efficient at securing land and constructing buildings. In terms of solar power generation, Daiwa House Industry has more than 15 years of experience, focusing on panel installations on roofs. Furthermore, Daiwa Energy, which was established in 1999, has built up power generation business experience through wind power generation facilities that have been set up across Japan.
Compared with structures such as large buildings, the construction of a mega-solar power plant is easier and hence provides a good chance for market entry to various companies. Amid such circumstances, Daiwa House Industry said it can demonstrate its strengths by achieving both safety and low cost through, for example, its technologies to create the strongest structure possible with the least amount of steel by leveraging its knowledge and expertise accumulated through being involved in the construction of many structures.
As described above, the on-roof-type system at Hibiki International Logistics Center is the first large-scale solar power plant that the Daiwa House Group, which has abundant knowledge in both building structures and solar power generation, has ever handled.
To prevent negative impact on roof coating
When setting up a solar power generation system on a roof, the Daiwa House Group gives priority to "limiting the impact on the building as much as possible," said Ryoichi Nishimoto, manager of the Property Management Group at Daiwa House Industry.
This is because Daiwa House Industry wants to prevent the situation where setting up a solar power system has a negative impact on a building owned and rented by the company, which is a building construction expert.
"To reduce the load on the building as much as possible" extends further than just limiting the impact on the roof structure and coating. It includes having no negative impact on roof maintenance for the next 20 years as long as the power generation business continues.
For example, the building could be damaged by rust occurring on a solar panel frame and spreading to the roof. Should there be signs of such a problem, the solar panel needs to be replaced immediately, Daiwa House Industry said.
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