Sunovia Energy Technologies, Inc. and EPIR Technologies, Inc. (EPIR) announce the development of new solar cell materials that Sunovia and EPIR believe will rival the most efficient multi-junction solar cell performance in existence today at significantly less cost. Sunovia and EPIR plan to accomplish this by uniquely combining the most prevalent photovoltaic (PV) semiconductors in the market today, cadmium telluride (CdTe) and silicon (Si), into a breakthrough multi-junction solar cell that leverages the economies of scale and manufacturing infrastructure that is associated with these materials. The enabling high-throughput manufacturing technologies for growing CdTe on Si have been proven by the University of Illinois at Chicago and successfully transferred by EPIR into night vision sensors over the past decade. Today, the technologies that have enabled the commercialization of night vision sensors and military superiority through "Owning the Night" are now being used to accelerate the development of next generation, multi-junction solar cell materials that position Sunovia and EPIR for "Owning the Daylight" in the future.
These breakthrough materials, which have been proven within night vision infrared (IR) systems for many years, will initially be applied to concentrator PV (CPV) systems with dramatically reduced price points from what is available today. The companies believe this will enable solar based electricity generation at prices equal to and even lower than current grid supplied power from non-renewable sources. CPV systems use optics and tracking mechanisms to "concentrate" the sun's rays into a smaller area, therefore requiring less solar cell material for the same amount of electricity as compared to a traditional flat-plate solar panel that does not use concentrator optics. As the deposition processes are further refined and increased in throughput, low cost high-efficiency solar cells for specialty and terrestrial applications using flat-plate systems, as opposed to CPV systems, will be commercialized. In the future, new materials and technologies will be applied in ultra-high volume deposition processes to create thin films on flexible substrates for residential, commercial and utility power generation products with very high production capacities and high velocity time to market deployments. The companies anticipate that revenues from IR materials will begin in 2008 with revenues from advanced CPV materials following after the IR technology is transferred to EPIR's next generation solar cell manufacturing facilities, currently in development.
Until now, semiconductors for PV applications have essentially come in two forms; high-efficiency, high cost solar cells created from multi-junction III-V semiconductors, and lower cost solar sells made from crystalline silicon and amorphous thin films. While II-VI solar cell materials such as CdTe have shown promise, the lack of suitable low cost substrates on which to deposit high quality single crystal thin films have relegated these very efficient materials to polycrystalline films having low-efficiency on heavy glass substrates. In contrast to the approximate 16% efficiency attained under the best conditions (and less than 10% efficiency in real world modules) at different laboratories for amorphous or polycrystalline CdTe solar cells, the EPIR calculations for single crystal CdTe solar cells gave an efficiency of 24% using realistic assumptions and numbers characteristic of CdTe of typical crystal quality for material grown on silicon by high throughput molecular beam epitaxy (MBE) deposition methods developed by EPIR. This efficiency was calculated assuming no antireflection coating and no back mirroring under a one sun intensity with a terrestrial solar spectrum and with the standard global tilt of 37 degrees (AM1.5G). The calculation was performed for a cell having a thin top layer of n-type CdS on 4 (Mu)m of p-type CdTe, the most common CdTe solar cell configuration. For a CdTe solar cell of a proprietary design, EPIR calculated an efficiency that is above 26%. EPIR believes a maximum efficiency above 30% is achievable for optimized two-junction CdTe/Si solar cells in which both the CdTe and the Si act as solar energy absorbers. The results of these detailed calculations indicate that the upper limits of energy conversion efficiencies of solar cells employing group II-VI semiconductors such as CdTe rival those of present solar cells using the corresponding group III-V semiconductors such as gallium arsenide (GaAs), with much greater manufacturability and significantly lower cost.
The companies believe the above results indicate that the EPIR CdTe/Si, and more generally II-VI based technology, has the potential to displace the high cost III-V based technology, particularly in CPV systems for power plants. The results also indicate that technologies based on EPIR's novel high throughput MBE deposition technique for growing epitaxial crystalline CdTe or CdTe/Si should displace the current amorphous or polycrystalline CdTe cells and Si cells, respectively.
Dr. J. Garland of EPIR Technologies, formerly Professor of Physics at the University of Illinois, states that "As an environmentalist, I am really excited by these results and by the rapid progress EPIR is making toward the manufacture of II-VI based solar cells. Renewable energy sources such as solar energy must be used to preserve the earth for future generations and for our national security. Solar power needs only a reduction in cost to turn the corner and become a primary source of energy here and around the world, and I believe that the EPIR II-VI technology can provide the necessary cost reduction."
Sunovia and EPIR have exclusively partnered to commercialize solar and IR technologies for the renewable energy and night vision markets. Sunovia is the exclusive marketer of all products, technologies and intellectual properties that are developed by EPIR, and currently owns a significant equity interest in EPIR. EPIR is the world leader in R&D on II-VI materials and devices for IR detection and imaging for night vision, missile tracking, exploration in space and other applications. The manufacturability of II-VI based IR focal plane arrays for IR imaging shows that II-VI materials grown by MBE have reached a maturity level worthy of solar cell production. Furthermore, EPIR has now completed a major facility for the manufacture of CdTe on silicon and for the development of improved solar cells based on II-VI materials.