Status and Recent Progress in Photovoltaic Manufacturing in the USA

This paper describes the present status of photovoltaic technology and recent manufacturing progress obtained through the U.S. Department of Energy’s Photovoltaic Manufacturing Technology Project (PVMaT). Although barriers to the widespread use of photovoltaics—a clean and renewable energy—continue to exist, many of these barriers are cost-related and can be addressed through further research on existing approaches. Important areas for development are new materials, improved manufacturing processes, more efficient conversion of sunlight to electricity, and ensured long-term reliability. Improvements in these areas can be expected to lead to lowering of system costs and, ultimately, of energy cost. Specific improvements in manufacturing processes by individual PVMaT participants are described. INTRODUCTION The study of photovoltaic (PV) technology has been a significant R&D area in the United States for about the past 25 years. At first, many people thought the ultimate areas of application would be large terrestrial installations similar in size to conventional power-generation facilities. However, during this time, smaller terrestrial applications have also become important, both as an initial market for PV systems and, in their own right, as new, essential applications (e.g., power supplies for telephones along highways, portable road signs, remote monitoring and communication systems, and individual residences). And although the advances in the technology have been noteworthy, barriers still exist to the widespread use of this relatively clean and renewable energy. Many of these barriers are cost-related and can be addressed through further research on existing approaches. Important areas for further development are new materials, improved manufacturing processes, more efficient conversion of sunlight to electricity, and ensured long-term reliability. Improvements in any of these areas can be expected to lead to lowering of system costs and, ultimately, of energy cost. This paper describes the present status of PV technology and some of the recent progress obtained through the U.S. Department of Energy’s Photovoltaic Manufacturing Technology Project (PVMaT). PHOTOVOLTAIC TECHNOLOGY STATUS Technology status for a developing technology like PV is characterized by the technical capabilities of the particular type of technology in terms of conversion efficiencies, as well as the production capacity and product cost. Cell and module conversion efficiencies are given below for various PV technologies. Also given in this section are collective historical data regarding the module cost and production capacity for participants in PVMaT. Information across the industry can also be found in various publications (see, for example, Maycock, 2000). Cell and Module Conversion Efficiencies For this discussion, PV technologies have been divided into three main areas: flat-platecrystalline silicon, flat-plate thin films, and concentrator (Witt, 2000). Flat-plate technologies include thick cells of crystalline silicon (from both ingot and sheet-growth techniques) and thinfilms (for this discussion, less than 100 micrometers) of various materials, usually deposited by some type of vapor deposition or by electrodeposition. Present thin-film approaches generally do