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1,000V System, Asphalt Cut Costs of Solar Plant

Hit by flooding from typhoon, unexpected snow cover in 1st year

2014/05/31 19:38
Shinichi Kato, Nikkei BP CleanTech Institute
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Shoken Co Ltd (Otsu City, Shiga Prefecture), a local general constructor centering on civil engineering in Shiga Prefecture, constructed two mega (large-scale) solar power plants: "Shoken Ishibe Solar Power Plant" (hereafter Ishibe Solar) in Konan City, Shiga Prefecture, and "Shoken Kashiwabara Solar Power Plant" (hereafter Kashiwabara Solar) in Maibara City, Shiga Prefecture. The capacity is approximately 1.811 and 1.995MW, respectively.

"By combining the two mega-solar power plants, the expected annual amount of power generation corresponds to about two-thirds the power our company consumes every year," Shoken President Mamoru Yamakawa said.

Shoken's mega-solar power plants have two major features. One is the entirely asphalted site (Fig. 1), and the other is that the solar power generation systems are built up with 1,000V-based components. These measures were adopted in an effort to lower both construction and operation costs.

It is unusual for a 2MW-class mega-solar power plant to adopt these specifications. Shoken Executive Director and Manager of Solar Business Tomoji Chihiro said, "We have always been positive about challenging moves as evidenced by the introduction of a plant that was twice as large as those of our industry peers and a cutting-edge manufacturing process in the asphalt business."

Shoken also kept its capital investment at roughly ¥600 million (approx US$5.9 millin) at "Ishibe Solar" and "Kashiwabara Solar," lower than other general mega-solar power plants, which were constructed at around ¥400 million per 1MW.

The procurement of business funds, which can reach hundreds of millions of yen, often forms a barrier to mega-solar power plant business by medium-sized enterprises, but Shoken said it provided all the funds itself. Partly because Shoken cut the initial investment per capacity, it is expected to recover the capital investment in about eight years.

Reason why fully asphalted ground can cut costs

The benefits of asphalting are the ease of solar power generation system construction and the reduction of construction costs. Moreover, it helps to prevent ground subsidence and reduces maintenance costs by preventing weeds after operation starts.

The ease of construction increases because asphalt makes the entire site flat, enabling stable construction even on rainy days and boosting the efficiency in conveyance and moving (Fig. 2).

A worker can transport secondary concrete foundations using a forklift and solar panels using a pallet jack to the positions to install them. At general unpaved mega-solar power plants, a team of two workers carry solar panels by hand. Compared to this, the carrying-in of related materials becomes easier because heavy machinery can be flexibly used.

The asphalt also enables tools and other items to be put on a trolley and installed one at a time, allowing workers to move around, as in a production line at a plant; this also leads to a shorter construction period and higher accuracy. By adopting Kyocera Solar Corp's inlay-style mounting system, a row of solar panels can be slid up to the designated spot like a sliding door and fixed by a bolt at both the top and bottom of the panels.

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