Simultaneous Construction of 5 Solar Plants Boosts Efficiency
Plants constructed on rich agricultural, dairy sites in cooperation with town
Fig. 1: Mibugawa Power Company's Tokachi Shimizu Solar Power Plant consisting of five power plants. Clockwise from upper left: Tokachi Shimizu Power Plant No. 1, Tokachi Shimizu Power Plants No. 2 to 3, Tokachi Shimizu Mikage Power Plant and Tokachi Shimizu Power Plant No. 4. (source: Mibugawa Power Company)
Fig. 2: The sites owned by the town were all easy to connect with the power transmission grid. In the photo, the generated power is connected with the grid just in front of Tokachi Shimizu Mikage Power Plant. (source: Nikkei BP)
Fig. 6: Connection boxes were also changed to fuse-type ones (right) that boast less power loss. Left is Tokachi Shimizu Power Plant No. 1, and right is Tokachi Shimizu Power Plant No. 4. (source: Nikkei BP)
Fig. 8: Measure against cold climate changed for air conditioners for PV inverters seen at both ends of the chassis (Tokachi Shimizu Power Plant No. 4). Compressor units for cold regions are covered with snow protection hoods without heating. (source: Nikkei BP)
The Marubeni Group started operating the "Tokachi Shimizu Solar Power Plant" in Shimizu-cho, Kamikawa-gun, Hokkaido Prefecture, Japan, in December 2013 to February 2014. The project consists of five solar power plants with an output ranging from 500kW to 1MW (Fig. 1) and forms a mega- (large-scale) solar power plant with a total output of 4.273MW. The power producer is Mibugawa Power Company (Chiyoda-ku, Tokyo), Marubeni Corp's wholly owned subsidiary engaged in small-scale hydroelectric power generation.
Mibugawa Power Company aimed at cutting construction and grid connection costs and achieving business sustainability by simultaneously building the neighboring five power plants even though the scale of each plant was just 1MW at the largest.
Accordingly, the project expanded to a total output of 3MW with Shimizu-cho introducing two privately owned sites in addition to the three sites owned by the town (Shimizu-cho). The town later gave up on the construction due to one site being difficult to connect with Hokkaido Electric Power Co Inc's (Hokuden's) grid. But the project further expanded to a total output of 4MW, 1MW more than the initial plan, after Shimizu-cho also swiftly introduced a replacement site. All these sites were easy to connect with Hokuden's power transmission grid (Fig. 2).
No power factor control, 5 plants connected with grid in 3 months
The five plants that form Tokachi Shimizu Solar Power Plant started operation one after another during the three month period from December 2013 to February 2014. Partly because it filed the application to Hokuden at an early stage, no plants have been requested to have a "power factor control", which regulates the output.
The Marubeni Group financed the total project cost of about ¥1.4 billion (approx US$13.6 million) through group loans. Engineering, procurement and construction (EPC) services were entrusted to Kinden Corp as a "full turnkey" contract (an EPC contract that covers every task concerning the construction).
Single-crystal silicon solar panels manufactured by LG Electronics Inc of Korea were adopted at all the plants except one, which used polycrystalline silicon panels manufactured by JA Solar Holdings Co Ltd of China. Although all five plants had initially planned to adopt LG Electronics' product, only the plant planned last adopted JA Solar's product as it was found that LG Electronics could not deliver its products to all of the five plants in a timely manner.
Marubeni serves as JA Solar's representative firm, but it employs the optimum power generation systems purely from the perspective of a power producer.
Toshiba Mitsubishi-Electric Industrial Systems Corp's (TMEIC's) PV inverters were adopted at all five plants.
Methods, positioning improved during construction in series
Shimizu-cho has a relatively small amount of snow cover for Hokkaido. Even so, it usually has snow in and after November. In light of this, the solar panels were tilted by 30° so that any snow on the panels would easily slip off (Fig. 4).
The ground side of the panels was set at 1.2m from the ground so that the snow slipping off from the panels would not accumulate and reach the height of the panels.
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