Solar Plants Produced With Progressive Municipality (page 2)
Technologies to cut construction period, cost
Fig. 1: Completion ceremony of "Takeo Hakamano Solar Power Plant" with approximately 1.5MW output, which started power generation in October 2013 in Higashi-Kawanoboricho, Takeo City. In the middle is Yasuhiro Yamamoto, senior executive officer and manager of Saga Office, Kyudenko. (source: Nikkei BP)
Fig. 3: Foundations were positioned in parallel at about 3.8m from each other to allow cement mixer trucks to drive around and directly pour concrete into molds no matter how narrow the space between the rows of solar panels. (source: Nikkei BP)
Both solar power plants adopted the Korean Hanwha Group's solar panels, Toshiba Mitsubishi-Electric Industrial Systems Corp's (TMEIC's) PV inverters and the mounting system of Hilti from Liechtenstein.
Kyudenko explained it employed the Hanwha Group's solar panels because of their low price as well as performance and warranty that are equivalent to those of Japanese products.
Kyudenko basically chooses TMEIC PV inverters at the mega-class solar power plants to which it provides EPC services.
"TMEIC focuses on the models compatible with power generation as large as 500kW output," said Masatoshi Motomatsu, manager of Renewable Energy Dept, Sales Div, Kyudenko. "We believe TMEIC is the top company in terms of reliability, pricing and procurement of PV inverters."
In particular, he cited the efforts to prevent the PV inverters from automatically stopping through detecting a fault on the power grid side. For example, many PV inverters automatically stop even though there is no malfunction in the plant's power generation facilities, if, for example, only the interconnected power grid momentarily went out due to lightning. In that case, the PV inverters have to be rebooted as soon as possible, or the amount of power sales would be reduced because the PV inverters would not start working.
The control system needed to minimize such a suspension, other than breakdowns, often varies according to the connected electric power company. TMEIC PV inverters can precisely adapt to such a control system by updating software and modifying the configurations and, as a result, minimize the risk of automatic suspension.
Hilti's mounting system is characterized by the small number of components to be assembled because the steel members forming the mounting system are modularized in advance. It features the ease of assembling that cuts the set-up time to about two-thirds compared with the conventional mounting systems manufactured by domestic companies. By cutting the construction time, the mounting system can help to reduce construction cost.
A plastic mesh like those used for selling oranges was arranged at the end of the steel members that support the longer edge of the solar panel arrays on the mounting system (Fig. 2). This is used to prevent birds from nesting.
Efforts to cut the construction period and lower the cost can also be found in the foundations. For example, a method to build the foundations by pouring concrete into a mold without post-processing was employed. This method is suited to cutting the time to build the foundations. The foundations are positioned at about 3.8m from each other so that cement mixer trucks can move along the space between the foundations and directly pour concrete into the molds on site (Fig. 3).
At other large-scale solar power plants, in many cases, cement mixer trucks cannot pass along the space between the foundations. In these cases, the time to build the foundations lengthens and the cost rises because pumper trucks are required to flow cement from the mixer trucks via pipes and hoses.
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