Visit to Plant

Double-sided Solar Panels Turn Snow Into Advantage (page 3)

Power generation efficiency improves even in winter

2014/02/09 15:24
Kenji Kaneko, Nikkei BP CleanTech Institute
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Based on the results of such verification tests and other factors, PVG Solutions concluded that the conversion efficiency of the panel using "EarthON" is about 18%, including the reverse side, when the ground surface is covered with snow, and 16 to 17% when the ground surface is soil, according to Director Shinji Horiuchi of PVG Solutions. Should the amount of reflection be increased by coloring the ground surface white, the conversion efficiency would reach the highest level among current mass-produced solar panels.

Nishiyama resolved to use the double-sided solar panel after visiting the verification site in Kitami City. He considered that snow would even reinforce the solar power generation business if the double-sided panel were used. To increase the amount of power generation on the reverse side of the panels during the seasons without snow, Nishiyama Sakata Denki is now considering scattering white materials on the ground.

Overcoming hurdles of securing site, fund-raising

Having entered the first winter since the double-sided panel-based mega-solar power plant started operation, it gradually became apparent that the panels are very effective in making snow slip off. It is already known that the cell temperature rises by 20 to 30° as the solar panel starts generating power, and thus melts any snow accumulated on the panel. However, once a large amount of snow fell at one time and accumulated on the panel, sunlight could barely reach the panel. In this case, the snow-melting effect accompanied with power generation cannot be guaranteed.

With the double-sided solar panel, however, the panel would generate power from the sunlight reflected onto the reverse side of the panel once the sun comes out, even after heavy snow. Then the panel temperature would rise and easily melt the snow on the panel. Although this had been expected, the effect gradually turned out to be larger than expected.

"After the plant started operation, the amount of power generation slightly fell short of the estimate in October," Nishiyama said. "But it has outperformed the estimates since November."

The plan to make snow assist the business is getting on track.

Nishiyama Sakata Denki's mega solar power plant business appears to be progressing smoothly at present. But it faced a number of challenges at the beginning. Besides the double-sided solar panel, the plant chose a reliable PV inverter manufactured by Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC) (Fig. 9). However, Nishiyama Sakata Denki initially faced difficulty in finding a site.

Although there are many large pieces of land around Asahikawa City, most of them are designated for agricultural use. The areas that are not specified as farmland are mostly unsunny and hence unsuited for a large-scale solar power plant. Nishiyama Sakata Denki was on the verge of giving up when Asahikawa City adopted its mega solar power plant proposal after a public appeal to use the grounds of a closed municipal high school.

The next challenge was fund-raising. Should Nishiyama Sakata Denki directly borrow funds from financial institutions, its capital adequacy ratio would decrease and its corporate rating would degrade as a result. This would make it difficult for the company to receive orders for public projects. Based on these circumstances, a method was applied in which an anonymous partnership financed a special purpose company (SPC) formed by a joint venture.

Through this method, the company succeeded in taking out ¥600 million (approx US$5.87 million) loans for the SPC from Japan Finance Corp and some regional banks. The challenges concerning land and fund-raising were solved this way. Nishiyama Sakata Denki's mega power plant business is likely to be a good reference for local enterprises in terms of both technology and fund-raising.