We have also written on solar concentrators, the coming of consolidation in the solar markets, inverter technology, and subsidy policy. And the fascinating look into the possible future of solar continues.
I had a chance recently to visit with one of the individuals responsible for International Business Machines Corp.'s (IBM) Big Green Innovations strategy – which has made a splash in the cleantech world over the last half year. We were talking on a range of topics, but one that piqued my interest was the description of IBM’s work in photovoltaics – and a few thoughts on where they were going. I did not ask, and he did not offer, any particulars on the work in progress, but he did make mention of a few points that I thought were well worth repeating:
• IBM is expecting to be a player in the solar cell business – likely seeing commercial impact in the next 18 months to two years.
• IBM is developing both advanced crystalline technologies and CIGS processes – relying on their semiconductor manufacturing expertise and nanotech research to make breakthroughs in controlling PV manufacturing processes.
• You will not likely see IBM making branded modules – perhaps instead a cell production business strategy?
• IBM sees the potential for very high efficiency multi-junction cells in foreseeable future.
The fascinating part is that IBM is not a newcomer to the game. When you do a little background research, you dig up some fascinating tidbits, including a couple of articles dated 1978 in the IBM Journal of Research and Development that are interesting, given the historical perspective they add to the discussion. For those still thinking that Silicon Valley venture capital is the real innovator behind the solar sector - see below.
As far as the mainstream (or even cleantech) press on IBM’s solar photovoltaic development, though, there has been little mention, and no details. News.com had a recent mention (but no details) of IBM’s solar interests (along with an oblique mention of their work in developing desalination membranes for the water sector). There was a brief mention of IBM and an organic solar cell development in a 2004 year old Business Week article. And a brief mention of interest in solar technology in an Information Week article about the IBM Innovation Agenda – which the Big Green Innovations is a part. But that's about it.
There are over a dozen recent US patents and published applications by IBM referencing a range of solar cells or photovoltaic technology, a few are listed below - that can give some indication of what work IBM has going on.
• 7,109,584 Dendrite growth control circuit
• 7,094,651 Hydrazine-free solution deposition of chalcogenide films
• 6,933,191 Two-mask process for metal-insulator-metal capacitors and single mask process for thin film resistors
• 6,875,661 Solution deposition of chalcogenide films
• 6,774,019 Incorporation of an impurity into a thin film
• 6,316,786 Organic opto-electronic devices
• 6,351,023 Semiconductor device having ultra-sharp P-N junction and method of manufacturing the same
• 20070057255 Nanomaterials with tetrazole-based removable stabilizing agents
• 20060032530 Solution processed pentacene-acceptor heterojunctions in diodes, photodiodes, and photovoltaic cells and method of making same
• 20050158909 Solution deposition of chalcogenide films containing transition metals
And here are the 1978 articles I promised above from IBM Journal of Research and Development. As I said - for those who still believe Silicon Valley is inventing solar.
Low Cost Silicon for Solar Energy Conversion Applications
Economically viable means of producing silicon solar cells for the conversion of solar energy into electric power are discussed. Emphasis is given to the discussion of crystal growth techniques capable of growing single-crystal silicon ribbons directly and inexpensively from molten silicon. The capillary action shaping technique [CAST]recently developed by IBM has a good potential for producing low cost silicon sheets suitable for solar cells. This technique has produced ribbon 100 mm wide and 0.3 mm thick. Problems that CAST must overcome in order to supply material for low cost solar cells are discussed. Economic and technological computer-modeled comparisons indicate that continuously grown CAST ribbons of these dimensions can meet a cost objective below $50/m2 of sheet material. The results require that it be possible to fabricate a twelve-percent-efficient solar cell from CAST ribbon 100 mm wide and 0.3 mm thick at a polycrystalline silicon cost of $10/kg.
Fascinating enough – while much earlier, this looks very similar to the Evergreen Solar (ESLR) story, whose success helped launch the recent venture capital rush into solar just a couple of years ago.
Growth of Polycrystalline GaAs for Solar Cell Applications
Films of polycrystalline GaAs have been grown on foreign substrates by the metal-organic process. The main objective was to produce films with as large a grain size as possible, so that high-efficiency photovoltaic devices may eventually be fabricated from such thin film/substrate structures. At 973 K, the average grain size was less than 1 µm, and was unaffected by the choice of substrate. Increasing the deposition temperature to 1123 K, while maintaining all other conditions the same, resulted in grains as large as 10 to 20 µm in diameter. Grain sizes as large as 10 µm could be obtained by precoating the substrates with thin films of evaporated gold or tin. However, both of these methods gave films that were discontinuous. A two-step procedure in which the films were nucleated at 873 K prior to growth at 1123 K yielded continuous films with an average grain size of 5 µm. Schottky barrier solar cells fabricated from these films exhibited short-circuit current densities as high as 15.7 mA/cm2, even though the highest conversion efficiency (AM0, uncoated) was only 1.3 percent because of the low fill factor (0.28).
Novel Materials and Devices for Sunlight Concentrating Systems
Photovoltaic conversion under concentrated sunlight is a highly promising technique that could make solar-electric power generation economically competitive with fossil fuel power generation by the mid-1980s. An economic analysis has been performed which demonstrates that solar cell efficiency, concentrator efficiency, and concentrator cost are the most important parameters in a concentrating photovoltaic system; solar cell cost is only of secondary importance (at least for Si solar cells). Six novel structures are described, including modified conventional Si cells, Ga1-xAlx As/GaAs devices, interdigitated cells, vertical and horizontal multijunction cells and "multicolor" devices.
So whether it’s high efficiency multi-junction cells to compete in the concentrator market, or organic or CIGS cells for BIPV, or providing advanced silicon cells to enable a new group of entrants into the rooftop module market, or something new entirely – IBM bears watching in the solar sector.