Sol Array LLC, a Delaware registered US company, has unveiled its first CIGS thin-film solar cell made using a unique and highly adaptable process, specifically tailored for mass scale production. The process uses commercially available, inexpensive soda-lime glass as substrate material; a simplified continuous in-line PVD process for of its entire CIGS thin-film stack, and a 4-element compound target for a simple one-step deposition; eliminating the extensive and subsequent selenization process, and doing away with the cumbersome co-evaporation of various CIGS elements for the formation of the active CIGS layer; thus ensuring consistency and repeatability in mass scale production and succeeding a highly efficient and low cost manufacturing format.
The company is yet to disclose its sample cell conversion efficiency, pending further verification and authentication of its tested sample, but early results is showing matching performance to current industry average. Sol Array LLC is strategically positioned for basing its research and patent 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, Mr. Jimin Ma has assembled a special team of seasoned thin-film technologists and automation specialists for product development and for system engineering.
The global thin-film Photovoltaics market, according to a recent report by NanoMarkets, is expected to reach $7.2 billion by 2015, compared to just over $1 billion in 2007; 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 surpassed CdTe and amorphous silicon by 2012, manifested by facts and events shown below:
- CIGS has the highest theoretical conversion efficiency; it can absorb over 99% of sunlight spectrum and it has the highest current density. CIGS ranks the highest in conversion efficiency for laboratory samples among all other thin-film solar technologies, where its latest record of 20.5% has been reported for small area experimental cell; although its success is yet to be proven for commercial production – an area of our special emphasis.
- CIGS is free from adverse environmental impact and it’s not threatened by the poisonous by-product such as Cd in CdTe thin-film cells.
- It has the potential, especially when employing our recommended process, to be the lowest cost for volume production – CIGS is amenable to large-area, automated production.
- CIGS films retain performance properties better than most other solar semiconductors.
Looking at the commercial solar industrial as a whole, there are ample evidences of a CIGS trend; where 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 the so call Alpha Phase CIGS is fast approaching maturity, efficiency hovering around 20% range; the immediate challenge rests more with the commercialization of CIGS cells, aiming for high volume, low cost, repeatable process that can promise economic vitality. SOL ARRAY LLC has a network of technology talent pools based in the US and other European research institutions for product development and research. 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.
Collaboration presently extends through the USA, Europe and China: with tailored vacuum deposition facilities aimed specifically for mass scale production considerations, with university liaisons, electro-optical & environmental testing facilities and with materials suppliers. SOL ARRAY LLC believes that the collaborative synergy lies in: technology exchange, corporate learning and market positioning, where its affiliations can leverage and amplify the core competencies of each participant, in areas of manufacturing, recruiting, process technology, marketing, research and development; where global competitiveness is pivoted on the proper balance of research, production and marketing that fuses the synergistic forces for long term endurance.
For commercially viable production method and to attain Alpha Phase CIGS thin-films, we expect to overcome these challenges:
- Repeatability in thin-film stack thicknesses and uniformity, where the combined thickness of our active layer is barely 1.8 micron, with our thinnest layer no more than 50 nanometer; where a precision controlled, pulse DC sputtering process is an ideal approach;
- Repeatability in stoichiometry among each thin-film layer is equally critical. Obtaining stoichiometry of the CIGS film reproducibly by other method has been difficult, especially over large areas. Work done by our affiliated research institute, employing Pulse DC Sputtering for all 4-elements compound deposition and without selenization, has shown remarkably good stoichiometry, 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 selellium, is critical; where Alpha Phase CIGS for instance can tolerate no more than 0.5% deviation in atomic weight of copper content – none other than a fully automatic, in-line system – with trim-down and simplified process steps – can come close to delivering the repeatability of such objectives;
- Repeatability in p-n junction formation at the suitable depth under the buffer layer, a rather stringent and difficult requisite for conventional evaporation techniques to synchronize, is replaced by our proprietary PVD process, ensuring a consistent interface between the p-type CIGS absorbing layer and the doped surface n-type layer near the interface CdS buffer layer.
- Commercialization calls for large scale, low cost production; our dense 4-element solid CIGS target and our custom process for high percentage material reclamation can give us lowest material consumption for volume production.
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.