Mitsubishi Plastics, Inc. (head office: Chuo-ku, Tokyo; President Hiroshi Yoshida) has recently developed a front sheet with an excellent water vapor barrier property (a water-vapor transmission rate of 10-4 g/(m2･day)) fundamental to flexible photovoltaic (PV) batteries. A supply process has been established to launch its commercial production: the sheet has already been employed for a flexible CIGS PV battery developed by Global Solar Energy Inc., Arizona, USA, and Mitsubishi Plastics will start to provide the full-scale supply of the sheet in 2012.

　It is estimated that the PV battery market will expand to 40-50 GW by 2015, led mainly by the crystalline silicon type. The market for flexible PV batteries that are lightweight and easy to form will be fully established in 2012, and account for 5% of the entire PV battery market by 2015. Flexible PV batteries that employ semiconductor compounds such as CIGS, in particular, are expected to play a central role in share expansion of the flexible PV batteries in the market due to their relatively low material costs as well as higher achievable conversion efficiencies (currently 13%). In order to prevent lowering of electric generation efficiency, these batteries require a front sheet that has the world’s highest level of water vapor barrier property with 10-4 g/(m2･day), which is one of the key factors to expand flexible PV market.

　Mitsubishi Plastics has successfully established a technology for super high gas barrier films in 2008 with a superior level of water vapour barrier with 10-4 g/(m2･day), by leveraging its gas barrier film production technology widely applied to back sheets for crystalline silicon solar batteries. To enter commercial mass-production and start full-scale supply of the film, Mitsubishi Plastics has invested approximately 2 billion yen to set up a new production facility in Tsukuba Plant (Ushiku-shi, Ibaraki Prefecture) in 2011. At the same time, the Company advanced the development of a front sheet with a water vapor transmission rate of 10-4 g/(m2･day), which is a key factor to expand the compound flexible PV batteries market. In the end, the commercialization of the front sheet has commenced through a contract with Global Solar Energy for their flexible CIGS PV battery called “Power Flex*”. The front sheet is formed of three or four layers including a core layer of gas barrier film. It has an excellent water vapor barrier property as well as other features necessary for front sheets including high weather resistance, ultraviolet absorptivity, fire retardancy and adherence property.

　Mitsubishi Plastics has a peerless mass production facility that can produce super high gas barrier films (maximum width of 1300mm) having a water vapor transmission rate of 10-4 g/(m2･day), with annual production capacity of 18 million square meters. Mitsubishi Plastics will further strive to expand the flexible PV battery market, by fully taking advantage of such a production facility. At the same time, as a group company of Mitsubishi Chemical Holdings, the Company continues to work closely with Mitsubishi Chemical Corporation, which is currently promoting its organic thin-film PV batteries, in order to actively expand PV battery materials business, of which products include sealing materials and films for back sheets.

* Power Flex is a registered trademark of Global Solar Energy Inc.

Photo: "Power Flex," a flexible CIGS PV battery developed by Global Solar Energy Inc.

Picture courtesy of Global Solar Energy

Inquiries by media regarding this material should be directed to the
Public Relations Section, General Administration Dept., Mitsubishi Plastics Inc.
TEL: +81-3-3279-3800