Overloaded by 1.4 times by securing additional site areas

From the south end and the highest point of the power plant's south site, not only the town of Hijimachi and Beppu Bay, but also the industrial area on the coast of Oita City across the bay can be viewed. However, the solar panels were set up like steps on the northern slopes facing inland, instead of the southern slopes stretching from the top of the hills toward the sea. Generally speaking, such location is not suitable for solar power generation (Fig. 3).

Fig. 3: Panels set up on reclaimed northern slopes (source: Nikkei BP)

"When designing the Fujiwara Yurino Power Plant, the major challenge was how to set up as many solar panels as possible on the northern slopes, which were not suitable for a mega-solar plant location," said Koji Watanabe, president of Hijidenki.

The plant's south site had originally been slated for a golf course. Having been put up for auction during the planning phase before construction began, its ownership transferred to a real estate company. Hijidenki purchased the site from this real estate company as a mega- (large-scale) solar plant site.

After the takeover, Hijidenki applied for prefectural permission to develop forestland under the Forest Act while considering civil engineering and reclamation as well as panel positioning layout. To increase the number of solar panels to be set up, the company made efforts to efficiently utilize space, such as even setting up panels in a reservoir to be constructed at a lower level, for example (Fig. 4).

Fig. 4: Solar panels even set up in reservoir (source: Nikkei BP)

Even so, it gradually turned out that the solar panel capacity would not reach 10MW, which was the grid capacity obtained when the facility was approved, if the company secures necessary reserve forest areas and a sufficient slope size focusing on safety.

Consequently, the company began to consider increasing the number of panels to be set up by leveraging the forest area on the adjoining north side in addition to the purchased site. Negotiating with multiple landowners and signing land lease contracts with them, Hijidenki eventually secured a new site where panels equivalent to a total output of 4.9MW could be set up in 11 blocks. As a result, the plant's panel capacity totaled 14.4MW, combining 9.5MW in the south site and the 4.9MW in the north site.