Visit to Plant

5MW Solar Plant Built on 26-degree Sloping Dam Wall

Slope specialists hired for construction

2016/06/21 15:21
Shinichi Kato, Nikkei BP CleanTech Institute
Print Page

In February 2016, Hyogo Prefecture Public Enterprises Agency started generating power at a 5MW-output mega- (large-scale) solar power plant on the wall of Kotani Dam in Toyotomicho, Himeji City (Fig. 1).

Fig. 1: Mega-solar plant set up on the body of Kotani Dam. A total of 19,580 panels were arrayed. (source: top Hyogo Prefecture Public Enterprises Agency, bottom Nikkei BP)

Kotani Dam was completed in 2000 and supplies tap water. It is a pumped-storage dam that pumps up and stores water from a nearby river when the river's level is high, and supplies the stored water to purification plants in times of water shortages.

At Kotani Dam, a solar power plant that leveraged a former borrow pit from the time of the dam's construction started operation in November 2014 (Fig. 2). This time, another mega-solar plant that uses the dam's body started generating power.

Fig. 2: A solar power plant that utilized a former borrow pit from the time of the dam's construction is situated along a mountain trail leading to the body of Kotani Dam. (source: Hyogo Prefecture Public Enterprises Agency)

Panels were set up on the "dam body" that plays the role of damming the water (Fig. 3). The body of Kotani Dam is a "rockfill dam" that was built by using rocks, stones, earth and sand as infill.

Fig. 3: Panels were attached to slopes built by using rocks, stones, earth and sand as infill. The top is before panel installation, and the bottom is after installation. The panels can generate power in conditions almost facing south and tilting by 30 degrees. (source: top Novac, bottom Nikkei BP)

Considering the plant is suited for solar power generation with the dam body facing south, Hyogo Prefecture decided to make the best use of the site as a place for a mega-solar power plant based on the feed-in tariff (FIT) scheme for renewable energy-based power generation.