To find out what’s happening on the materials side, I spoke with Tom Earnest, marketing manager for DuPont Photovoltaic Solutions in Wilmington, Del. He indicated that there appears to be no letup in the demand for PV materials. Just five or six years back, growth in the PV market was only around 20 percent, but now it is at about 70 percent or more. Dupont’s Tom Earnest talks about the materials side of the photovoltaic industry.Hindsight being what it is, materials manufacturers have focused on photovoltaics for several years in anticipation of the upswing. In fact, the materials used for photovoltaics are not much different from those used for computers or other electronic devices, but the catch is that they’re needed in massive quantities at low prices and must be able to withstand sunlight and other elements for 25 years or more. To meet these demands, DuPont has invested in expansions and new research and development facilities globally. The most recent addition was the opening of a new technical center in Taiwan for the development of thick-film metallization pastes for photovoltaics. The drivers, according to Earnest, are aimed at lower cost per kilowatt-hour or per watt of power. One approach to getting higher efficiency out of a PV module made with the new pastes is to focus on lower losses and higher conductivity. The other he described as “taking up less space on the silicon.” When a paste is applied to the front of a silicon cell, it covers part of the cell that’s supposed to be absorbing sunlight. So a major research effort is focusing on application technologies that will print thinner lines of the paste to shade less of the silicon. Tweaking the processFine-tuning the process of applying materials is one way the industry can get the most bang for its buck. Materials manufacturers like DuPont are working on better application methods and are looking at ways of moving product through the factory more quickly. We may be using cutting-edge technology and thinking “outside the box” to increase use of solar energy, but people in the industry tend to be conservative around materials selection, Earnest contends. They expect a device to perform at a high level for 20 to 30 years, so they look for materials with a record of reliability in other applications. In the global quest to decrease use of fossil fuels ASAP, there’s no time to perform long-term reliability testing of new materials. So using traditional materials customized in new ways for PV is the way to go. One change is the move from traditional crystalline silicon PV technology to the emerging amorphous silicon thin-film PV market. Earnest sees this market growing at close to 100 percent or more a year. A key to thin-film technology is decreased use of materials. According to Earnest, a very thin film can be 1 percent or less of the active PV material, resulting in an inherent cost advantage. Despite the fact that less material may be required, materials manufacturers such as DuPont are supporting the shift, recognizing that driving down the total installed cost of PV power is the most critical factor in ensuring continued strong growth in the PV market. The industry has learned a lot from hindsight. The demand for PV power is real and will continue to grow. By using established materials in new ways to improve efficiency, by developing improved process technologies that enable more cost-effective manufacturing, by expanding capacity and by encouraging innovation, materials manufacturers can ensure the continued success of PV as an energy source.
Photosensitizers