Solar Plants Damaged by Typhoons in Summer (3)
Mounting systems also damaged by flooding
Continued from Solar Plants Damaged by Typhoons in Summer (2)
9 plants affected in potential flood damage areas
Strong typhoons again hit Japan one after another in summer this year. Some solar power plants were severely damaged by the typhoons. In the first half of this report, sites where panels and mounting systems were damaged by the strong winds are introduced, mainly covering the story of Typhoon No.15. In the second half, sites damaged by flooding caused by Typhoon No.19 are reported.
In respect to damage to solar power generation facilities caused by Typhoon No. 19, 18 accidents were reported in accordance with the Electricity Business Act, of which 16 were hazards caused by flooding. An advisory panel of experts at the Ministry of Economy, Trade and Industry (METI) reported that "nine of the 16 flood damage cases occurred at plants constructed in potential flood damage areas."
Solar power plants are more vulnerable to water damage than earthquake damage, and therefore, areas along rivers with a high risk of flooding and coastal areas by the Pacific Ocean with a high risk of tsunami were often excluded as candidates for solar power plant sites. This trend will become stronger in the future (Fig. 1).
Low-voltage solar power plants damaged by Chikuma River embankment bursting
According to the report, 16 sites were damaged by flooding caused by Typhoon No. 19. But they are only the tip of the iceberg because high-voltage and extra-high-voltage solar power plants that are 50kW or higher in output are required to be in the report under the Electricity Business Act while low-voltage plants for business use from 10kW to less than 50kW, which are large in number, are not included in the report.
It is impossible to grasp the whole picture of damage to low-voltage plants for business use, but we can get a glimpse of the damage from the severe flooding caused by the Chikuma River embankment bursting in Nagano City, where the scale of damage due to the flooding caused by Typhoon No. 19 was large.
In the severe flooding in areas in Nagano City along the Chikuma River, the embankment burst over a distance of about 70m, flooding areas that extend from south to north by a span of 1km. When we visited the areas in late October after the disaster, at least six low-voltage solar power plants for business use that were within 2km of the burst embankment were damaged by flooding.
The locations of the six sites are shown by characters A to F in the map. Two of the sites are in a residential area about 300m from the burst embankment (A, B). Two are along a main road located about 1km from the embankment (C, D), and two are along an agricultural road located about 1.5km from the embankment (E, F) (Fig. 2).