Solar power from external walls / New material allows for more efficient energy production (Yomiuri, 4.1.2012)

Mitsubishi Chemical Holdings Corp. plans to sell a new type of external building material that generates power from sunlight beginning in fiscal 2013, it has been learned. Unlike conventional solar panels, whose installation sites are limited to roofs and other specific places, the new material can be used for walls of buildings and other structures in sunny locations. The new material will likely boost the spread of renewable energy. If the material is used for skyscraper walls, just one or two buildings could produce electricity equal to that generated at a large-scale solar power plant, according to experts.

The new material has been developed thanks to the company's creation of solar cells that use organic semiconductors made from petroleum and other materials instead of the silicon semiconductors currently in use. The new cell is thinner and lighter than current panel-type cells.The cells' power generation capability is about 80 watts per square meter, and their efficiency in converting solar energy to electricity is about 11 percent, a level sufficient for practical use. For comparison, conventional solar panels have an efficiency of 14 percent to 15 percent.

Organic solar cells are easier to manufacture than current solar panels that use heavy base materials such as glass. Experts said the production cost of the new cells could be as low as one-tenth of the panels. The new cells can be used not only for walls but also on small roofs or parking lots where large conventional panels are difficult to install. The new cells also have strong earthquake resistance.

The company also plans to use the cells in the bodies of electric vehicles and in curtains. Conventional external wall materials that generate power using silicon semiconductors are costly and their efficiency in converting solar energy to electricity is low. As Mitsubishi Chemical sells wall materials in more than 100 countries and territories, the company expects the new material to promote the broad use of solar power.