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1st Project Finance for Agricultural Mega Solar Plant Revitalizes Idle Farmland (2) (page 3)

2017/11/30 20:43
Kenji Kaneko, Nikkei BP Intelligence Group, CleanTech Institute
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Power generation capacity increased 15% by incorporating single-shaft tracking-type mounting systems

Shimin Energy Chiba has also been developing technologies related to solar sharing. The company incorporates foundations and mounting systems designed for solar sharing by Akira Nagashima, who was formerly a designer and developer at a major agricultural machine manufacturer and currently represents CHO Technical Research Institute.

The mounting systems that are 2.5 to 3.5m in height are built by assembling single pipes in structures similar to wisteria trellises. Narrow solar panels of about 24 cells (power generation elements) are arranged on the mounting systems. The shading rate becomes approximately 30% if the distance between the strip-shaped panels is set at two times the panel width. Nagashima developed this system in 2004 and applied for a patent.

However, joints in the mounting systems built with single pipes are fixed by joint brackets, and the issue of strength and durability had to be solved. As a solution, four single pipes were fixed diagonally as a brace to all joints between supporting pillars and beams to enhance the strength.

Shimin Energy Chiba developed and commercialized its original couplers for use as braces to enhance the strength and workability (Fig. 10).

Fig. 10: Special couplers were developed for use as braces for single pipes. (Source: Nikkei BP)

"If the structure is configured so that farmers can assemble and repair it by themselves, the installation cost will be reduced significantly and business feasibility will improve," Azuma said. "If farmers operate solar sharing plants on their own farmland, feasibility will be ensured even if the tariff drops below 20 yen/kWh."

Nagashima, who created the prototype of the wisteria trellis-type solar sharing equipment, developed a single-shaft moving-type (tracking-type) mounting system in 2014 in collaboration with Shimin Energy Chiba and other entities. Panels on the conventional wisteria trellis-type mounting systems are installed facing south because the panels are fixed to them. However, panels on the moving-type mounting systems are installed facing east or west because the panels move from east to west in line with the movement of the sun.

The moving-type mounting systems are already incorporated in the agricultural power plant operated by EGpower, and are connected to low-voltage power lines (Fig. 11). The panels move automatically from the east to directly above (horizontal) and then to the west, tracking the sun, between 9:00 in the morning and sunset. The panels are horizontally positioned on days with strong wind due to typhoons, etc, and on cloudy days. Based on the results up to now, the moving-type mounting systems improve the power generation capacity by about 15%.

Fig. 11: Panels are fixed facing east or west on the newly developed moving-type (tracking-type) mounting systems. (source: Nikkei BP)

New challenges, in terms of organization and technology, have arisen for effective sharing of the sun by crops and panels. The district, where the amount of abandoned farmland was increasing due to poor soil fertility, becoming a burden to the region, has become the mecca of solar sharing and is developing into an advanced area highlighting new farming methods.