World-Record Solar Panel Efficiencies

World-Record Solar Panel Efficiencies Heartening news for the solar PV sector came through on Friday, Sept. 25, with a number of companies reporting solar efficiencies undreamed of a decade ago. A solar cell's energy conversion efficiency is the amount – written as a percentage – of solar insolation, or sunlight, converted from light to electrical energy.In the multi-crystalline silicon photovoltaic (PV) category, Suntech is announcing a conversion efficiency of 16.53 percent, a result verified (for aperture area only) by the Fraunhofer Institute for Solar Energy Systems (ISE), Europe’s largest solar energy research institute.Suntech's module is powered by Pluto PV cells, Suntech’s proprietary, patent-pending approach to silicon cell manufacture. The process uses solar-grade silicon to achieve potential efficiencies of more than 17 percent. In March, the Pluto PV 34-megawatt manufacturing line achieved reported efficiencies on monocrystalline silicon cells of 18.8 percent, also confirmed by Fraunhofer ISE. These results put Suntech at the top of the conversion-efficiency pyramid.Another manufacturer of crystalline PV cells, German-based Q-Cells SE, has achieved an efficiency rating of 15.9 percent for its 249-watt polycrystalline solar module – a rating that represents a paradigm for industry-standard mass-produced solar cells. Again, the certification is from Fraunhofer ISE, with the breakthrough coming out of research at the company’s $73.6-million Tehnikum module test center built last year.Q-Cells high-performance polycrystalline cells, which have potential efficiencies up to 17 percent, are expected to hit market in 2010 at the conclusion of the development portion of R&D, at which time efficiency ratings may prove even higher.IMEC, a solar cell manufacturing partnership between Total and GDF Suez and their manufacturing arm, Photovoltech, have developed a multijunction Gallium Arsenide/Germanium (GaAs/Ge) stacked cell with a potential 40 percent efficiency between its GaAs top cell (23.4 percent) and Ge bottom cell (3.5 percent).Again, the goal is to have a working model early in 2010, with conversion efficiencies up to 2 percent higher than what is currently being delivered, using concentrated illumination. The “enhanced spectral robustness” (IMEC’s description) is the result of stacked cells made from the different materials, each of which captures a particular band, or wave length, of light.Fraunhofer ISE itself has developed a (thin film) prototype n-type (semiconductor layer) silicon solar cell with efficiencies in excess of 23.4 percent. The n-type, or “doped” silicon cell, eliminates the problem with impurities generally faced by crystalline solar cells, via the addition of boron or aluminum, the latter element eliminating the front passivation associated with silicon dioxide or silicon nitride in the p-type base of the cell. The process also includes screen printing the aluminum layer, and further advances in manufacturing technology could boost overall efficiencies closer to 20 percent by the time the product reaches the market.Thin-film maker Oerlikon Solar has also reportedly set a world record for amorphous silicon (a-Si) single junction PV cells, as tested by the U.S. Department of Energy’s National Renewable Energy Laboratory, or NREL, of more than 10 percent. Oerlikon’s Neuchatel, Switzerland-based R&D department has been able to consistently reproduce cells with this exact efficiency, and its repeated success will allow it to achieve reliable and persistent production.Sunovia Energy Technologies, Inc. also announced on Sept. 25 that it had fabricated single-junction and two-junction cadmium telluride-based (CdTe) solar cells that surpass the world record for open circuit voltage (Voc) thin films by more than 45 percent.Voc performance metrics have traditionally been the most difficult to optimize in CdTe cells, so the achieved open-circuit voltage efficiency (in the 1.34 V value), of more than 95 percent of the theoretical upper limit, tops Voc values of 76 percent of theoretical maximum previously achieved. Sunovia and its partner, EPIR Technologies, Inc., view this achievement as pushing solar energy ever closer to grid parity.Sunovia, however, did not provide information on independent confirmation of their results.