Consumer Co-op Realizes Mega Solar Systems on Logistics Facilities

High yield using Japanese panels, PV inverters

2014/03/31 15:23
Kenji Kaneko, Nikkei BP CleanTech Institute

Osaka Izumi Co-operative Society based in Sakai City, Osaka Prefecture, boasts the largest-class size among consumer co-ops across Japan, with 453,257 member households (as of the end of March 2013) and supply value of ¥69 billion (approx US$671 million) in fiscal 2012. Its activity area is south Osaka, extending from Higashi-Osaka City to Misakicho.

There are two large logistics centers: "Techno Stage Logistics Center" and "Ayumino Logistics Center," located in Izumi City, which is situated in the heart of the area. The former is a facility featuring refrigerator functions, which was completed in 2003, while the latter is a room temperature facility completed in 2012.

Osaka Izumi Co-op constructed 2.3MW of mega (large-scale) solar power plants on the roof of these two logistics centers. The output is 1.3MW at Techno Stage Logistics Center and 1.0MW at Ayumino Logistics Center. Construction started in July 2012, when the feed-in tariff (FIT) program was launched, and finished with operation starting in November that year (Fig. 1 & 2). Tess Engineering Co Ltd (Yodogawa-ku, Osaka City) designed and constructed the plant, while Kyocera Corp's solar panels and Toshiba Mitsubishi-Electric Industrial Systems Corp's (TMEIC) PV inverters were adopted.

In the wake of the Fukushima nuclear disaster, the Japanese Consumers' Cooperative Union (JCCU) announced its "proposals for Japan's energy policy" in January 2012. In the proposals, JCCU cited the "diffusion of solar power generation" as one of its prospective efforts in local areas. Amid such a trend, nationwide consumer co-ops have embarked on setting up solar power systems. Osaka Izumi Co-op, in particular, has been leading this approach.

Can consumer co-op run power generation business?

Yoshio Hamada of Osaka Izumi Co-op confessed, "Given the large number of members who focus on the diffusion of reusable energies, we had received quite a few requests. Although we once set up solar panels with a few kilowatt-output at headquarters, they were really just some sort of symbol. So, we continued discussions based on business sustainability, simulating investment recovery in view of solar panel installation on the roof when we constructed the Techno Stage Logistics Center in 2003. We gave up on the plan because then there was neither the FIT program nor sufficient returns."

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Under these circumstances, the co-op started to move with a definite purpose based on its belief that the project could become feasible as the direction of the FIT program began to show in summer 2011.

As the co-op made its move ahead of other consumer co-ops in Japan, it also ran into an obstacle: the issue of whether the power selling business could be approved as a co-op operation to begin with. Consumer co-operatives rules specify that they run their business targeting co-op members under the Consumers' Co-operative Livelihood Law. Should the co-op generate solar power and connect to the Kansai Electric Power Co Inc's grid to sell the generated electricity, the power would be used not only by the co-op members but also by others.

Regarding this point, Osaka Izumi Co-op sought confirmation from the local office of the Ministry of Health, Labour and Welfare, via the Osaka Prefectural government, and found out it could run the business as long as "the amount of power sold does not exceed the power demand by the overall co-op members."

After confirming a co-op can embark on a power selling business, Osaka Izumi Co-op started selecting a company to order the EPC (engineering, procurement and construction) service. Comparing and examining proposals by different enterprises, the co-op finally decided on basic design specifications such as output scale and installation method, requested quotations from three candidates and chose Tess Engineering.

The basic design specifications included the 1.3MW and 1.0MW outputs of the panels to be mounted on Techno Stage Logistics Center and Ayumino Logistics Center, respectively. And the installation method was that the panels would be directly attached to the folded-plate roof. Should the panels be installed to face south at an angle of 20 to 30° using mounting systems on the roof, the amount of power generation would increase, but the construction cost would also sharply rise.

The co-op said it worked out that the method to install the panels almost directly flat onto the roof would be the most beneficial when giving priority to boosting the cost-effectiveness and accelerating investment recovery.

EPC constructor Tess Engineering has grown through and has a good track record in cogeneration (combined heat and power) system installation and maintenance. As for solar power generation systems, Tess Engineering had constructed small-scale facilities at clients’ plants to which it had delivered cogeneration facilities even before the implementation of the FIT program.

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However, Osaka Izumi Co-op was the first institution to which Tess Engineering ever provided EPC service for a mega-solar power plant with an output exceeding 1MW. Tess Engineering chose Kyocera's solar panels because of their past accomplishments after examining mainly domestically produced products (Fig. 3). Tess Engineering said it also adopted TMEIC's PV inverters as it highly appreciated TMEIC's broader lineup compared with other manufacturers of large PV inverters, their reliability and accurate delivery time (Fig. 4).

1MW achieved by spreading panels across roof

Although this was the first mega-class facility for Tess Engineering to deal with, it had previous experience in many designs that directly set up solar panels on folded-plate roofs using clasps. The form of foldings in the folded-plate roof had been standardized, and the clasps to hold parts and materials to the roof were also general-purpose ones.

Based on the calculated clasp strength and resistance to wind pressure, four to six clasps were used to hold each panel (Fig. 5). Tess Engineering said that considering the panels, cables and other facilities installed on the roof, which weigh 21kg per 1m2, the roof had sufficient strength.

All across the roof of Ayumino Logistics Center, you can see the solar panels beautifully arrayed. The roof is almost exactly the right size for 1MW worth of solar panels. Accordingly, the roof gives the impression that it is almost completely covered with panels. Unlike most other blue polycrystalline silicon panels, Kyocera's panels look blackish due to their proprietary surface finishing technology, which is aimed at preventing reflection. The appearance of the roof, covered in chic black, is magnificent (Fig. 6).

At a glance, the panels appear to be set up flat, but in fact they are tilted at 2 to 3°. The folded-plate roof was originally tilted at 2 to 3° with the aim of making rainwater drain off. As the panels are directly secured to the tilted roof, they are also tilted at the same angle that efficiently drains rainwater. Since Kyocera's panel design sets slits on the edge of the frame so that rainwater can easily drain off with any dirt, it is suited to an installation at such a low angle.

Amount of annual power generation exceeds expectations by 1.3 times

What became an issue when starting construction in July was the heat. The temperature of the steel plate used for the folded-plate roof exceeds 70°C under the sun during the day, with the ambient temperature nearly reaching 50°C. Working for hours on the roof under these circumstances could cause heatstroke.

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At Ayumino Logistics Center, in particular, there is no shade due to the lack of ancillary equipment on the roof. The number of heatstroke patients in Japan is increasing. And many of the victims are elderly who are weak and who have worked for long hours under the sun.

Hence, Tess Engineering initially programmed a process timesheet in which almost no work was carried out on the roof for one and a half months from mid-July to August. Recognizing the ambient temperature does not rise so much from 5 am and in the late afternoon through evening, even in midsummer, however, Tess Engineering continued with the construction on the roof in the morning and evening, taking a rest in between. As a result, the construction, which had been slated to end in December, was completed one month earlier, and selling electricity started on November 2.

The amount of power generation at the mega-solar power plant of Osaka Izumi Co-op outperformed the initial estimate by as much as 30% in the year after the completion (Fig. 7). In the initial business plan, the co-op planned to secure two-digit IRR (internal rate of return) to recover its investment in nine years.

Behind the plan was the realization of a 2MW-class mega-solar power plant, which is a high investment efficiency project, on its own buildings. In addition, a significant contribution was made by closely studying the solar power generation business at an early stage, establishing a trusting relationship with the EPC constructor and comprehensively collaborating with said constructor.