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Mega-solar Power Plant Plagued by Vines (page 2)

Picket-based panel installation changed to foundation-based method

2014/04/06 12:22
Shinichi Kato, Nikkei BP CleanTech Institute
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"When selecting a candidate construction site for a mega-solar power plant, we have maintained a system in which we promptly propose the project to the head of the owner company immediately after understanding solar radiation conditions and other factors important for solar power generation and researching whether the site has a mortgage or not as soon as we find a desirable site," said Director Minoru Kubo, Comsys Create.

The company once abandoned the construction of a mega-solar power plant despite having reached an agreement with landowners. The reason was because of the barrier of land use categories.

"It was land that neither the landowner nor the agricultural committee of the local city recognized as farmland," said Tsugunori Kondo, manager of the Development Business Div, Comsys Group Power Generation Business Dept, Comsys Create. "Only after we had announced our construction project and started to investigate the land and proceed with construction did we have to abandon the project when the land was recognized as farmland just because some leaseholder of the land once farmed there. There must be quite a few power producers and landowners who are confused by the ambiguity of the Agricultural Land Act that can easily be affected by such judgments by municipalities and agricultural committees."

Foundation varied by ground condition

At Hitachiota Solar Power Plant, A site is in a position down from B site (Fig. 2). At each of these sites, 1,392kW-equivalent solar panels were set up despite PV inverters with a rated output of 990kW. Installing solar panels with an output (nominal maximum output) exceeding the rated output of PV inverters is called "overload."

In solar power systems, the amount of power sold always falls short of the total value of the nominal maximum output of the panels even on a sunny day due to system loss. Furthermore, panel output further drops on cloudy days or in the morning and late afternoon. Under these circumstances, installing panels with an output exceeding that of PV inverters is effective as it can boost the utilization rate of the PV inverters as much as the amount of the power generation rises, increasing the amount of power sold at the same time.

Keeping the installation angle of the solar panels as small as 15°, Comsys Create arrayed 4,800 panels with 1,392kW output in each of the two sites.

To maximize the amount of power generation per panel, the optimum installation angle in Japan is considered to be 30°. Solar panels tilted at 30°, however, would require a broader space for each row as the impact of shadows over the panels in the rear row would grow. As a result, the number of solar panels that can be set up in the same size area would decline.

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