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February 13th, 2007
Nanotechnology & Solar Power News: 2006 & January 2007
To continue this thread, at the IEEE San Francisco Bay Area Nanotechnology Council meeting on January 16th Dr. Homer Antoniadis, CTO of http://www.innovalight.com, announced that Innovalight's silicon nanocrystalline ink holds the promise to bring flexible solar panels to less than $0.40 per watt.
Technical issues include manufacturing silicon & other nano particles reliably & at the required cost & scale. Scaling up to wide, large length rolls in roll to roll manufacturing is not a trivial issue and requires time to get a manufacturing process both to work and to get yield to economic levels. While Dr. Antoniadis did not give a timeline, I felt that he expected (and certainly his VC backers expect) to have large-scale manufacturing & product to market before 2015.
Other start-up companies that plan to use nano particles include two in Silicon Valley, Stion & Solexant. Stion has the backing of both Vinod Khosla, the well-known Tier 1 Silicon Valley venture capitalist as well as Moser Baer, a major CD manufacturer in India
Moser Baer Photo Voltaic of India is apparently taking a 20%-ish stake in Stion Corp (formerly NStructures), a Silicon Valley-based nanotech startup focusing on solar photovoltaics. Khosla Ventures and Braemar Energy Ventures participated in NStructures' Series A financing. This is the third equity investment by Moser Baer Photo Voltaic, after taking equity positions in solar concentrator technology firms Solaria and SolFocus. (source, http://www.insidegreentech.com - November 16, 2006)
Solexant is developing high efficiency low cost nanostructured solar cells. Solexant solar cells achieve high efficiency by incorporating nanomaterials that harvest light from the entire solar spectrum and achieve low cost by adopting roll to roll manufacturing process. (source, http://www.nsti.org/press - Presenter Profiles, May 4, 2006.)
And the original start-up (2001) targeting solar PV by using nanostructured tripods, Nanosys, http://www.nanosysinc.com/app/index.html, is apparently still moving forward with work in this area: "One potential product is a new type of solar cell that performs like a traditional solar cell, but can be configured like a light weight, flexible plastic. In particular, this technology has the potential to provide low cost solar power through currently available, high volume and inexpensive manufacturing techniques based on conventional film based processes such as roll to roll manufacturing. To develop our nanotechnology-enabled solar cells we are collaborating with several United States government agencies."
On another note Sharp announced a major breakthrough in a-Si technology on January 25th (source, http://www.physorg.com/news ) Sharp Corporation has successfully developed mass-production technology for stacked triple-junction thin-film solar cells by turning a conventional two-active-layer structure (amorphous silicon plus microcrystalline silicon) into a triple-junction structure with amorphous silicon (two active layers) and microcrystalline silicon (single active layer). This new architecture boosts cell conversion efficiency from 11% to 13% and module conversion efficiency from 8.6% to 10%. Mass production is slated to begin in May 2007 at Sharp's Katsuragi Plant in Nara Prefecture.
To put this announcement into perspective, please review the NREL September 2006 review of SPEC-SHEET RATINGS, From Manufacturers' Websites (Claims not verified) below. These efficiencies may be considered best cases. Particularly interesting is the Temperature Coefficient - the standard module efficiency ratings are measured at 25 degrees C or 72 degrees F. The Tcoeff gives you the loss in efficiency for each rise in degree C. That is, solar cells and modules have an optimal operating temperature and as the temperature rises, for example to 50 degrees C or 122 degrees F - the top rated Sunpower module declines in efficiency by 25 x 0.38% = 9.5%, reducing actual operating efficiency from 17.7% to 8.2% at this temperature.
Clearly there is a lot of room for improvement in solar cell & module technology, including various approaches to cooling solar cells at high temperatures, better materials, better device designs, better manufacturing processes & so on. At the SEMI nanoforum staged October 31 to November 2, 2006 in San Jose, senior technical speakers from both Konarka http://www.konarka.com and Nanosolar http://www.nanosolar.com stressed the importance of manufacturing efficiencies, including CAPEX, throughput, & yield. Both speakers expressed serious doubts about the long term viability of the current c-Si paradigm by pointing out that while the semiconductor industry relies upon 100x - 1,000x markup on the price on their raw material, the c-Si solar PV industry raw material cost is on the order of 20% - 25% today, allowing a markup at module selling prices on the order of 4x to 5x.
Both speakers presented the case that only roll to roll manufacturing, similar to the process used in printing newspapers, can deliver the manufacturing efficiencies required to dominate the solar PV market in the long run. This topic will be covered in another column.
Finally it is interesting to see in the February, 2007 edition of Scientific American, page 11, that Angela Belcher's group at MIT http://belcher10.mit.edu/index.htm is working on solar cells, having already developed leading edge technology for self assembly of flat panel display and battery elements by using viruses & phages to create controlled nanostructures. "Solar cells are a major focus in our work at MIT right now. We are trying to take advantage of biology to template different materials in a very small space and in close proximity to act as full spectrum solar absorbers."
Please send your feedback, ideas, and suggestions to Bo Varga via
Bo has 28 years experience developing business strategy, funding, & strategic alliances for start-up and early stage companies in Silicon Valley & globally.
He has six years experience with the commercialization of nano technology & clean technology ventures & a very strong interest in helping clean energy & clean technology water projects.