Visit to Plant

Rooftop Solar Plant Prevents Roof Damage From Typhoon (Part 1) (page 3)

No power generation for 3 weeks due to heavy snow

2019/05/21 10:17
Shinichi Kato, Nikkei BP Intelligence Group, CleanTech Labo
Print Page

METI refuses to approve replacement of panels broken by typhoon

Following the typhoon, the company discovered the cover glass of one solar panel had been broken among the panels on the rooftop (Fig. 5). This is the only panel that has ever broken at the rooftop mega-solar plant in Kofu.

Fig. 5: Solar panel with broken cover glass (source: Nikkei BP)

Although the cause is not yet known, the company believes that the typhoon's strong winds caused an object from outside the warehouse to hit the solar panel.

Not only is the cover glass broken, but also some areas are burnt due to cell (power generation element) damage in the broken solar panel (Fig. 6). The burns appear to have been generated after the cover glass was broken.

Fig. 6: Electrodes and part of back sheet burnt (source: Nikkei BP)

No damage from heavy snow in 2014, but power generation stopped about 3 weeks

The plant has been struck by heavy snow. However, the company's previously mentioned efforts to boost load bearing costs proved effective (Fig. 7).

Fig. 7: Following heavy snow in February 2014 (source: Saito Warehouse)

In February 2014, about six months after the operation began, record-breaking heavy snow fell for two consecutive weeks in the Kanto-Koshin region. The average snow cover in Kofu City reached 1.40m. The second snowfall accumulated on the roofs at the warehouse before the first snow cover completely melted.

After the heavy snow, the tenant companies focused on restoring the warehouse first so it could again operate as usual. What proved effective was the roofs' load bearing capacity which had been reinforced more than necessary.

The load bearing capacity required to mount solar panels on the roof was about 14kg/m2. This value is equivalent to the weight of water on the rooftop up to 1.4cm in height. However, the actual load of snow is even heavier. If the reinforcement had been limited to the minimum, the reinforced areas might have been damaged, according to the company. Part of the frieze boards on the roof bent as a result, but the roofs themselves remained intact.

About three weeks after the second snowfall, the snow on the panels could finally be removed as a lot of the panel surfaces became visible. The company had refrained from removing the snow on the panels until then, because it could not secure areas to dump the snow removed from the roof, which was about 10,000m2. As a result, the plant could only generate sufficient power for about one week during this month until it was hit by the first snowfall.

Facility overview

Go to next page