Yingli Green Energy Holding Co Ltd was incorporated on August 7, 2006 in the Cayman Islands as part of a restructuring of the equity interest in Tianwei Yingli to facilitate investments by foreign financial investors in Tianwei Yingli. The Company completed its initial public offering on June 13, 2007. The Company and its subsidiaries are engaged in the design, development, marketing, manufacture, installation and sale of photovoltaic (PV) products in the People's Republic of China (PRC) and overseas markets. Its products are Polysilicon Ingots and Blocks, Polysilicon Wafers, PV Cells, and PV Modules. A polysilicon ingot is formed by melting, purifying and solidifying polysilicon feedstock into a brick-shaped ingot. The Company produces 400 kilogram, 540 kilogram, 560 kilogram, 600 kilogram and 800 kilogram multicrystalline polysilicon ingots, which account for approximately 90% of its ingots. The Company use its polysilicon blocks to produce polysilicon wafers. The polysilicon blocks are then sliced into wafers with wire saws. Thinner wafers enable a more efficient use of polysilicon, and lower the cost per watt of power produced. The wafers are generally available in the size of 156 millimeters x 156 millimeters. A PV cell is a device made from a polysilicon wafer that converts sunlight into electricity by a process known as the photovoltaic effect. The conversion efficiency of a PV cell is the ratio of electrical energy produced by the cell to the energy from sunlight that reaches the cell. A PV module is an assembly of PV cells that are electrically interconnected, laminated and framed in a durable and weatherproof package. Currently, its PV modules are made with PV cells produced by the Company. The Company faces competition in the PV modules and PV system markets and its PV products compete with different solar energy systems as well as other renewable energy sources in the alternative energy market. It competes with both local and international producers of solar products, including the solar energy divisions of large conglomerates such as Sharp Corporation, PV module manufacturers such as SunPower Corporation, thin film solar module manufacturers such as First Solar, Inc. and integrated PV product manufacturers such as SolarWorld AG, Renewable Energy Corporation and Trina Solar Limited.