Integrated Monitoring System Employed for 10MW Solar Plant
High-speed, large-volume data processing at a low cost using building management system
Fig. 1: Approx 10MW-output mega-solar "Ako Solar Power Plant" built in an industrial park on the former salt farm. The beautiful sight of neatly arrayed solar panels. (source: upper by Shimizu, lower by Nikkei BP)
Fig. 2: The state of power generation by each string being displayed in different colors that grow redder as it approaches full output so anybody can immediately recognize the situation. Display examples on April 8, 2014. The upper left is around 7:45, the upper right is around 10:50 when the output was full, the lower left is around 14:20 when the output started to fall and the lower right is around 17:30 when power generation is almost over. (source: Shimizu)
Ako City, Hyogo Prefecture, is known as the land of Chushingura (otherwise known as the Forty-seven Ronin) as well as the town of "Ako salt," for which salt farms once spread across the Seto Inland Sea. Nishihama Industrial Park was also developed on a former salt farm, which is a 10-minute drive from Banshu-Ako Station on JR West's Ako Line.
Leading general constructor Shimizu Corp built "Ako Solar Power Plant," a mega (large-scale) solar power plant with an output of approximately 10MW, at the site and started selling power in April 2014 (Fig. 1).
The construction site extends to 160,314m2, which corresponds to about four times the size of Koshien Stadium, home to a professional Japanese baseball team. Shimizu had acquired the site with a plan to build a subsidiary's plant, but gave up on the plan and eventually left it idle.
Locations with abundant sunshine are suitable for salt farms where salt is made by evaporating seawater. Needless to say, Nishihama Industrial Park enjoys abundant sunshine throughout the year, and a stable amount of power generation could be expected if a mega-solar power plant were to be constructed there.
3.5 billion yen construction cost financed by Dai-ichi Life Insurance through subsidiary
This was the first solar power generation project for the Shimizu Group; however, it had already been engaged in engineering, procurement and construction (EPC) services for mega-solar power plants for some time. The Shimizu Group is slated to provide EPC services for Japan's largest class mega-solar projects such as the 116MW-output plant being constructed in Rokkasho Village, Aomori Prefecture, and the 250MW-output plant on the former Kinkai Salt Farm in Setouchi City, Okayama Prefecture.
Ako Taiyoko Hatsuden (Chuo-ku, Tokyo), a special purpose company (SPC) financed by Shimizu, is the power producer of Ako Solar Power Plant. The project cost of roughly ¥3.5 billion (approx US$34 million) was procured from Shimizu Group financial subsidiary Shimizu Finance.
For the Shimizu Group, Shimizu Finance provides financing needed for the group's projects including construction. Shimizu Finance raised the funds needed for the construction of this solar power plant from Dai-ichi Life Insurance Co Ltd. Shimizu expects to recover the initial investment in about seven years.
System integration to be 'essential for 10MW or larger power plants'
Ako Solar Power Plant integrated various systems required for estimating the power generation situation and the amount of power generation. As long as the systems are integrated, all data are transmitted through one optical fiber cable with data transmission technologies integrated as well. Such a system is unusual.
At many mega-solar power plants, the power generation situation is monitored and confirmed with respect to each PV inverter or "string" that connects between 11 and 19 solar panels in series.
Some cutting-edge mega-solar power plants, on the other hand, have introduced a system to monitor the connected power grid or predict the amount of power generation, a video-based ITV (industrial television) monitoring system and a security monitoring system.
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