Floating Mega Solar Plant Pushed to Shore by Typhoon in Saga

2019/10/22 01:26
Kenji Kaneko, Nikkei BP Intelligence Group, CleanTech Labo
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About half of mounting systems damaged by strong typhoon winds

Typhoon No. 17, which formed off the southern coast of Okinawa Prefecture Sept 19, 2019, passed over the ocean to the north of Okinawa on the 21st and went through Tsushima Straits in the evening of the 22nd. The typhoon caused extensive damage to the Okinawa, Kyushu, Chugoku and Shikoku regions. In the Kyushu region, strong wind with a maximum instantaneous wind velocity of around 40m/s was recorded in Nagasaki and Saga prefectures on the night of the 22nd.

In Shiroishi Town in Saga Prefecture, the "Shintaku Tameike MS Power Plant," a floating mega solar power plant with 2,376kW of solar panel output, which was in operation on the agricultural water pond "Ariake Reservoir," was severely damaged by the strong wind. The wind pushed the floating mounting systems toward the northern shore of the pond, scattering many mounting systems and panels.

At the mega solar power plant, each of the solar panels was installed on one floating mounting system, and an island almost square in shape was formed by connecting the units consisting of a solar panel and a floating system. The island of panels was floated on the northeastern area of the pond and was fixed to the bottom of the pond by connecting anchor cables to the ends of the island.

The island was floating 10 to 15m from the shoreline on the northern side and 20 to 30m from the shoreline on the eastern side, but the northern end of the "island" reached the shoreline of the pond (Fig. 1).

Fig. 1: Floating mounting systems pushed against northern shoreline of pond. Picture shows scene after removal of scattered mounting systems and panels. (source: Nikkei BP)

According to an estimation based on the disaster situation, the strong wind tilted the southeastern end of the square panel island toward the eastern shoreline and pushing the entire island toward the northern shoreline. Floating mounting systems that reached the shoreline were pushed by the mounting systems behind them several meters over the land.

Mounting systems at the front hit the concrete fence between the pond and the road around the pond, rolling over and lying on top of one another. It is believed that the joints between the mounting systems and panels were partially disconnected during the process and scattered across the water surface and the shoreline (Fig. 2).

Fig. 2: Panels originally 10m from shore. Picture shows scene after removal of scattered mounting systems and panels. (source: Nikkei BP)

While being swept away to the north, many of the floating mounting systems that were not fixed by anchor cables at the ends of the panel island were turned over and scattered by the strong wind.

About half of the floating mounting systems were shifted from the water surface to the shore or turned over. However, none of the solar panels and floating mounting systems were scattered beyond the fence around the pond (Fig. 3).

Fig. 3: Distributed PV inverters also swept away with mounting systems. Picture shows scene after removal of scattered equipment. (source: Nikkei BP)