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Integrated Monitoring System Employed for 10MW Solar Plant (page 2)

High-speed, large-volume data processing at a low cost using building management system

2014/06/09 13:07
Shinichi Kato, Nikkei BP CleanTech Institute
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Fig. 1: Approx 10MW-output mega-solar "Ako Solar Power Plant" built in an industrial park on the former salt farm. The beautiful sight of neatly arrayed solar panels. (source: upper by Shimizu, lower by Nikkei BP)
Fig. 1: Approx 10MW-output mega-solar "Ako Solar Power Plant" built in an industrial park on the former salt farm. The beautiful sight of neatly arrayed solar panels. (source: upper by Shimizu, lower by Nikkei BP)

Fig. 2: The state of power generation by each string being displayed in different colors that grow redder as it approaches full output so anybody can immediately recognize the situation. Display examples on April 8, 2014. The upper left is around 7:45, the upper right is around 10:50 when the output was full, the lower left is around 14:20 when the output started to fall and the lower right is around 17:30 when power generation is almost over. (source: Shimizu)
Fig. 2: The state of power generation by each string being displayed in different colors that grow redder as it approaches full output so anybody can immediately recognize the situation. Display examples on April 8, 2014. The upper left is around 7:45, the upper right is around 10:50 when the output was full, the lower left is around 14:20 when the output started to fall and the lower right is around 17:30 when power generation is almost over. (source: Shimizu)

Fig. 3: The concrete foundations were efficiently made using metal molds. The size was expanded to boost load resistance in the outer rows, where wind pressure is high. (source: Nikkei BP)
Fig. 3: The concrete foundations were efficiently made using metal molds. The size was expanded to boost load resistance in the outer rows, where wind pressure is high. (source: Nikkei BP)

Fig. 4: A maintenance road was set up in the middle for operational efficiency. (source: Nikkei BP)
Fig. 4: A maintenance road was set up in the middle for operational efficiency. (source: Nikkei BP)

Fig. 5: This space is being kept without solar panels to prevent a building that might be built next to the plant on the west side from shading the solar panels in the afternoon. (source: Nikkei BP)
Fig. 5: This space is being kept without solar panels to prevent a building that might be built next to the plant on the west side from shading the solar panels in the afternoon. (source: Nikkei BP)

Fig. 6: In accordance with the land slightly sloping toward the drainage area in the plant, the height of the solar panels was varied by row. (source: Nikkei BP)
Fig. 6: In accordance with the land slightly sloping toward the drainage area in the plant, the height of the solar panels was varied by row. (source: Nikkei BP)

Fig. 7: The cable rack was raised as high as the foundations as a measure against flooding. (source: Nikkei BP)
Fig. 7: The cable rack was raised as high as the foundations as a measure against flooding. (source: Nikkei BP)

Fig. 8: A pipe-based mounting system adopted for verification (source: Nikkei BP)
Fig. 8: A pipe-based mounting system adopted for verification (source: Nikkei BP)

Facility overview
Facility overview

When introducing several monitoring systems like this, data was previously transmitted by each system's transmission technology. The cost for introducing different systems and transmission cables as well as for their maintenance has been a challenge for the plants that use several different monitoring systems.

Ako Solar Power Plant enabled the entire data transmission via one cable, integrating those systems into one. A building energy management system (BEMS) was utilized. This move was aimed at accelerating data transmission and lowering cost by integrating multiple monitoring/analyzing systems and large-volume data into one management system.

Cost benefits from the integrated system can be expected at 10MW or larger mega-solar power plants. Its introduction is likely to become a requirement at mega-solar power plants of this size.

For example, the plant currently displays the measured situation of power generation per string in real time (every minute) on the overall plant map in different colors using this system so the situation can be immediately recognized (Fig. 2).

Should a problem cause some strings to show a sharp drop in the amount of power generated, it can be easily recognized by a different color tone. Featuring the capabilities to compare such information as weather changes, temperature and the amount of sunshine with the expected amount of power generation, the system will further improve its prediction accuracy.

6 months to set up from foundations to panels

Approximately 12MW-equivalent 48,342 single-crystal silicon solar panels manufactured by Sharp Corp and 20 PV inverters by Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC) have been installed at Ako Solar Power Plant.

Sharp's solar panel was selected because its performance and warranty, compared with others, were superior among the single-crystal silicon panels that boast relatively high power generation efficiency. As for the reasons why it adopted TMEIC's PV inverter, the plant cited its reliability backed by overwhelming achievement and performance it has shown at other mega-solar power plants in Japan and high compatibility with Sharp's solar panels.

The mounting height was set at 50cm from the ground. This is because the builders could set up panels by standing without ladders or other tools. According to the plant, this will make it easier to maintain the installation accuracy and stability, shorten the installation time and eventually lower construction cost.

The foundations were made by placing molds and pouring concrete into them on site (Fig. 3). Compared with the method that uses wooden frames, the cost would rise, but it can boost accuracy and cut the time to make the foundations.

Given the 9,208 foundations required for the roughly 10MW-class plant, the cost increase could be absorbed. Seventy molds had initially been used, but the number was increased to 150 to raise the pace of making the foundations.

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