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1.4MW Solar Plant Withstands Snow, Strong Wing in Hokkaido

Lesson learnt from panel blown away by strong wind

2014/07/05 21:36
Kenji Kaneko, Nikkei BP CleanTech Institute
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The construction of "TY (Technical Yield Co Ltd) Obihiro Taisho Solar Power Plant" (Fig. 1) in Nakajima-cho, Obihiro City, was initiated in September 2012 and completed in February 2013. Yamauchigumi Co constructed the plant, setting up 4,550 single-crystal silicon solar panels (1,205kW-equivalent) manufactured by Yingli Green Energy Holding Co Ltd. Five PV inverters (250kW type) made by GS Yuasa Corp were also installed. Although the rated capacity is 1,250kW, the contracted amount of power to be sold to Hokkaido Electric Power Co Inc was kept at 990kW.

The plant adopted a spiral pile-type foundation (Fig. 2). The rigidity was secured by burying the piles 1.5m into the ground. The area has less snow cover compared with other areas in Hokkaido, yet it still sees 30 to 50cm of snow cover about five times a year. In light of this, the panels were tilted by 40° so the snow on the panels would slip off, and set up at 1.5m high so the fallen snow would not reach the panels (Fig. 3). The snow on the panels naturally slipped off when the sun came out after the snow had fallen, as had been expected. However, the snow on the panels sometimes did not drop off when the fallen snow piled up and reached the panels. Accordingly, the plant needed to regularly remove the snow under the panels using heavy machinery.

Panel, PV inverter manufacturers switched to Choshu Industry, TMEIC

TY Obihiro Taisho Solar Power Plant has smoothly generated power, achieving a facility utilization rate of about 15% per year, surpassing Japan's average of 13%. Nevertheless, TY had to revise some points and introduced different designs and facilities at its second mega-solar power plant "TY Sarabetsu Solar Park," which was completed in December 2013 (Fig. 4).

The company further raised the height of the solar panels from the 1.5m to 1.8m so it could reduce the frequency of snow removal (Fig. 5). It also changed the pile-type foundations to another method that buries 1.2m-high concrete blocks (secondary product) 1m into the ground (Fig. 6). The reasons behind the shift were that it took longer than expected to build the pile-type foundations, partly because of the quarry stone at the first site, and the rigidity turned out to be reinforced by switching to the concrete blocks through careful intensity calculations.

TY also boosted the system efficiency by raising the direct voltage of the solar panel circuit from 600V at the first site to 1,000V. Choshu Industry Co Ltd's single-crystal silicon solar panels and two units of 630kW PV inverters manufactured by Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC), the market leader in mega-solar power plants in Japan, were adopted (Fig. 7). The mounting systems and the foundation blocks were manufactured by Kitanihon-Sash Co Ltd and Tokachi Toyonishi Concrete Seihin, respectively.

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