News Article
Sol Array’s PVD Process Produces Cheap & Efficient CIGS Solar Cells
The firm has unveiled its first CIGS thin-film solar cell made using a unique PVD process, specifically tailored for mass scale production.
Sol Array’s process uses commercially available, inexpensive soda-lime glass as the substrate material. The firm uses a simple continuous in-line PVD process for deposition of all of its CIGS thin-films stack and a 4-element compound target for one-step deposition.
This eliminates the cumbersome co-evaporation of various CIGS elements for the formation of the active CIGS layer, ensuring consistency and repeatability in mass scale production, thus providing a highly efficient and low cost manufacturing process.
The company is yet to disclose its sample cell conversion efficiency as further verification and authentication of its tested sample is pending, but it says early results match current industry standards.
Sol Array says it is strategically positioned for basing its research and patenting revenue in the US market and its scale-up production in Dong Guan, China, where substantial government stimulus program beckons. Headed by a veteran in the flat panel display industry for over a decade, Jimin Ma has assembled a special team of seasoned thin-film technologists and automation specialists for product development and system engineering.
The global thin-film Photovoltaics market is expected to reach $7.2 billion by 2015, compared to just over $1 billion in 2007, according to a marketing report by NanoMarkets. Annual thin-film solar production has now exceeded half the US market share and will do so worldwide by 2015 and, within the thin-film solar industries according to "Information Network" CIGS should surpass CdTe and amorphous silicon by 2012.
According to Information Network, CIGS has the highest theoretical conversion efficiency as it can absorb over 99% of sunrays and has the highest current density. CIGS ranks the highest in conversion efficiency for laboratory samples among all other thin-film solar technologies, although its success is yet to be proven for commercial production.
Furthermore, a CIGS efficiency of 20.5% has been reported for small-area, experimental cells, by far the highest efficiency among all thin-film solar technologies. CIGS is also free from adverse environmental impact and it's not threatened by the poisonous by-product such as Te in CdTe thin film cells.
CIGS has the potential, says Sol Array, especially when employing its manufacturing process, to be the lowest cost for volume production making it suitable for large-area, automated production. The firm also claims that CIGS films retain performance properties better than most other solar semiconductors.
Looking at the commercial solar industrial as a whole, there is much evidences of a CIGS trend; major players such as Honda Soltec, Shell, Daystar, Ascent Solar, Global Solar, HelioVolt, Miasole and Nanosolar are all pursuing CIGS for their scale up production.
For laboratory research, the pursuit of so call Alpha Phase CIGS is fast approaching maturity, hovering around 20%+/- range, the immediate challenge rests more with the commercialization of CIGS cells, aiming for high volume, low cost, and a repeatable process that can promise economic vitality.
Sol Array has a network of technology talent pools based in the US and other European research institutions for product development and patent revenue; the company has established China as its primary manufacturing base, not only for the benefit of long term production cost control, but more importantly, in capturing the blossoming market expansion within China's insatiable energy market needs.
Collaborators of Sol Array are based in the USA, Europe and China, with tailored vacuum deposition facilities aimed specifically for mass scale production. Institutions include universities, electro-optical & environmental testing facilities and materials suppliers.
The core management of Sol Array has been shifted from the former thin-film flat panel display company, Lite Array where the cross fertilization of the founding team, between the thin-film display industry and the thin-film solar industry, ensures the Company a high yield, high volume and highly cost-effective solar cell production process.
For a commercially viable production process and to attain Alpha Phase CIGS thin-films, Sol Array has overcome a number of challenges. The pulse DC sputtering process is ideal for repeatability in the thin-film stack thicknesses and uniformity. The combined thickness of the active layer is less than 1.8 microns, with the thinnest layer less than 50 nanometers.
Repeatability in stoichiometry among each thin-film layer is equally critical; the experiments carried out in an affiliated research institute, employing Pulse DC Sputtering for all 4-elements compound deposition and without selenization, has proven successful, delivering a high density, pin-hole free thin-film stack.
The percentage proportion of each of the 4-element compound active layer: in copper, indium, gallium and selenium, where Alpha Phase CIGS can tolerate no more than 0.5% deviation in atomic weight of any particular element content is equally critical - none other than a fully automatic controlled process can come close to delivering the repeatability of such objectives says Sol Array.
Repeatability in the crystal lattice arrangement is a difficult requirement to meet for conventional evaporation techniques but the firm’s PVD method makes it easier to fulfill.
Furthermore, the process is claimed to ensure a consistent interface between the p-type CIGS absorbing layer and the doped surface n-type layer near the interface CdS buffer layer.
A 20 MW pilot production line, employing the aforesaid process and system engineering, will commence in early spring 2011 pending infusion of addition capital to be raised from various on-going funding activities.
Sol Array is an international player in solar photovoltaic R&D, product development, scale up production and system design. Collaborations presently extend through the USA, UK & China, with vacuum deposition facilities, university liaison & materials suppliers. Other institutions are also involved in the electro-optical & environmental testing of modules.