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Solar Revenue From Prefecture-financed Plant Expected to Benefit Locals (page 4)

Aiming to return 900 million yen in revenue to local community

2013/10/29 11:47
Kenji Kaneko, Nikkei BP CleanTech Institute
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Proprietary "Earth Plate" development

Shobara Solar Power Plant is located in Shobara City in the Chugoku Mountains, where the temperature often goes below 0°C in winter and the gap is large between cold and warm periods. The area also has a lot of snow, with even 1m of snow recorded in the past. In light of such weather conditions, along with the expected returns to the local community, the plant gave more consideration to long-term operational stability compared with other general solar power plants located in flat areas run by private enterprises.

Its single-crystal silicon solar panels are manufactured by Mitsubishi Electric and feature enhanced weather resistance. Mitsubishi Electric listed the output volume by panel, inspecting every panel before shipment, and removed the panels that could not demonstrate the rated output.

The panels were tilted at 20° on the mounting system so snow would slip off. The lower side of the panel and the ground are spaced 85cm apart so the snow slips from the panel and does not pile up higher than the panel. The mounting systems are positioned about 2m from each other for the purposes of keeping the panels from shading other panels and boosting working efficiency by leaving space for vehicles to pass.

The adopted PV inverters are a product of Toshiba Mitsubishi-Electric Industrial Systems (TMEIC). Its maximum efficiency reaches 97.7%. The efficiency of PV inverters becomes low in some models when the amount of irradiation is small due to clouds and other factors. But TMEIC’s PV inverters maintain high efficiency even when there is not much sun.

Meanwhile, cost-cutting efforts can also be seen everywhere throughout the plant. Each array (a group connected via the same wiring) consisting of 16 solar panels is laid on a mounting system with only four posts. The posts are held rigidly with screw pickets screwed 2m into the ground.

Panels are usually connected with each other by earth cables to release electricity. But Shobara Solar Power Plant succeeded in lowering costs and problems soldering earth cables by developing a proprietary hardware dubbed "Earth Plate" and inserting this between the mounting system and the panels at their joints to ensure power distribution to the mounting system.