Solar Plants Produced With Progressive Municipality (page 3)
Technologies to cut construction period, cost
Fig. 1: Completion ceremony of "Takeo Hakamano Solar Power Plant" with approximately 1.5MW output, which started power generation in October 2013 in Higashi-Kawanoboricho, Takeo City. In the middle is Yasuhiro Yamamoto, senior executive officer and manager of Saga Office, Kyudenko. (source: Nikkei BP)
Fig. 3: Foundations were positioned in parallel at about 3.8m from each other to allow cement mixer trucks to drive around and directly pour concrete into molds no matter how narrow the space between the rows of solar panels. (source: Nikkei BP)
Solar panels set up without filling in depression
Some arrangements were also made in accordance with the location at Takeo Hakamano Solar Power Plant. Alongside an expressway, the power plant is situated in a rectangular site facing southeast on the long side, in the central area of which has a deep, rectangular depression extending along the perimeter.
Should solar panels be arrayed and oriented directly to the south in such terrain, it would cause two problems. One is the inability to lay out all the panels for an output of 1.5MW as planned due to the dead spaces created at the site's corners when the panels are not installed squarely in the rectangular space. The other is the need to install panels in the same way even in the depression.
The layout and construction became complicated due to the slopes in the area where the foundations were placed. Furthermore, it was difficult to build the foundations that Kyudenko deployed on slopes. Accordingly, Kyudenko finally decided to lay out the panels facing southwest, which was the option that enabled most panels to be installed.
According to Kyudenko, the construction cost would have been lower if the depression in the central area had been filled in and evened out. However, considering the cost to restore the site to its original state after the termination of the 20-year power generation business, Kyudenko chose to leave the depression as it was and mount the panels at the same height by devising the mounting system (Fig. 4 & 5).
The height of the mounting system was raised only in the depression. The cross-section of the depression looks like a basin with a flat bottom and a steep slope on both ends of the depression. And Kyudenko avoided constructing the mounting systems in the middle of the slope and using a design that would require delicate height arrangement for the mounting systems.
The height of the mounting system was about 25cm, and the solar panels were tilted at 10° on the mounting system.
Kyudenko sets a reference term of power generation facility construction at about one month per 1MW, but announced it took two months to build this facility due to the construction process having taken the depression into consideration. Although the company has not revealed the construction cost, it seems not to have exceeded Kyudenko's reference cost of approximately ¥300 million (approx US$2.9 million) per 1MW.
Meanwhile, Takeo Wakaki Solar Power Plant was constructed on flat land. Partly because of a request by the city, the plant is designed to educate people on solar power generation and the environment. The plant site's peripheral road is accessible to automobiles and pedestrians. And an observation deck was set up at the end of the road so that visitors can enjoy a panoramic view of the related facilities, including the solar panels across the site, PV inverters and the connecting points to the grid of Kyushu Electric Power (Fig. 6).
Boards to explain the mechanism from power generation to transmission and introduce the function of each facility were set up in front of the observation deck and other facilities (Fig. 7).