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Light-weight Panels Realize Japan's Largest On-roof Solar Plant (page 2)

Mountable area expanded on roof of glass substrate plant

2013/12/28 19:15
Shinichi Kato, Nikkei BP CleanTech Institute
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Cover glass thickness reduced by 75%

If the weight of a solar panel were reduced, the load capacity required to install solar panels could be lowered, and the number of roofs that can be equipped with panels would greatly increase. There would be the possibility of introducing an on-roof-type solar power generation system to buildings and houses on which the owners have, thus far, not been able to mount solar panels because of their poor load capacity. In addition, the density of installation can be raised on the roofs on which the density of solar panels was restricted.

Specifically, many roofs on which the solar panels were installed this time had a load capacity of 20kg/m2 or more. On these roofs, Mitsubishi Electric Corp's existing solar panel, which weighs 21kg per panel or 12.5kg/m2, was installed (Fig. 2). However, some roofs only had a load capacity of 10kg/m2. Due to the load capacity, the existing solar panel weighing 12.5kg/m2 could not be set up on these roofs. Accordingly, Fujipream Corp's solar panel, whose weight was cut by about half to 9.5kg per panel or 6.4kg/m2, was installed on these roofs.

Of the 70,000m2 roofs mounted with solar panels, light-weighted roofs account for about 13,000m2. The 20,906 crystalline silicon solar panels installed consist of 16,226 existing panels by Mitsubishi Electric (about 4MW) and 4,680 light-weight panels by Fujipream (about 1MW).

According to Asahi Glass, some roofs' load capacity was low depending on the purpose of the building, not when the building was constructed. The company had some reasons not to give priority to the load capacity, such as there being no need to attach a crane on the roof and the necessity to quickly complete the building.

The light-weight solar panel uses Asahi Glass' chemically enhanced glass "Leoflex" as cover glass. This product achieved a thickness of 0.8mm, a sharp reduction from the existing model's 3.2mm. The weight was 75% less than that of the existing model. But its features such as the cover glass strength were maintained.

The weight of the cover glass accounts for 70% or more of the overall weight of a crystalline silicon solar panel and, therefore, is a major factor when cutting the weight of a solar panel. Asahi Glass not only supplied glass but also offered other information including that on its optimum usage.

On the other hand, there is the problem that this new glass costs more than the existing cover glass. But the cost is expected to decline as its deployment increases because Leoflex is manufactured by the float process just like glass substrates for LCD panels and it can easily generate a volume-production effect.

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