Visit to Plant

Riverside Solar Plant Facilities Survive Flood of River (page 2)

Remote monitoring of PV inverters added after automatic recovery failure

2019/10/29 14:56
Shinichi Kato, Nikkei BP Intelligence Group, CleanTech Labo
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Power generation facilities not submerged despite flooding in site

The solar plant has been struck by heavy rain, which exceeded initial estimates, putting the mega-solar plant's rainwater treatment and drainage function to the test.

The mega-solar plant said it had primarily undertaken two procedures on the ground of its site to improve maintenance efficiency and enable proper treatment and drainage of rainwater. Each procedure was designed to realize an appropriate balance between different elements.

The plant improved maintenance efficiency by asphalting near the perimeter of the site (Fig. 4). Compared with conventional mega-solar plants that are entirely covered by earth, it became easier to set up related facilities and equipment, while inspection and replacement efficiency also increased.

Fig. 4: Perimeter area asphalted (source Nikkei BP)

The power plant only asphalted the perimeter area in consideration of cost and the impact on power generation. If the whole site was asphalted, panel temperatures might rise due to heat reflection from the asphalted ground and result in a further decline in power generation during high summer temperatures.

Given these circumstances, the ground under the panels was roller-compacted and covered with crushed stones instead of asphalt (Fig. 5).

Fig. 5: Surface compaction over crushed stones (source: Nikkei BP)

From the design phase, the plant took measures to discharge rainwater out of the site. First, it built a new reservoir at the south end in addition to the existing reservoir that had been used since the site was a quarry. Furthermore, the plant developed the site so it would slope from north to south. In this design, rainwater would run through the drainage ditch southbound from the north and eventually pour into the reservoirs.

In addition, the ground under the panels was dug out slightly. Because of the clayish soil, the ground does not drain well. Accordingly, the plant made water pooling easier by further digging the ground under the panels.

In case of heavy rain, this design allows rainwater to pool not only in the two reservoirs through the drainage ditch, but also under the panels so the solar panel area can also play the role of a reservoir. The solar panels, combiner boxes and cables between them were fixed at a height taking this pooling effect into consideration (Fig. 6).

Fig. 6: Combiner boxes, electric cables supported a little higher (source: Nikkei BP)