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Thin film PV breakthrough may cut solar costs by one third

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A new Silicon Valley developer of thin film solar PV modules, backed by an Australian venture capitalist, has claimed an engineering breakthrough that could cut the manufacturing costs of PV modules by one third.

RSI has broken cover after five years of development to announce it has created a 1.5 square metre cadmium telluride PV (CdTe) module, twice the size of conventional modules.

It says this will enable solar PV modules to be manufactured at a cost of less than 40c/Watt, around one third cheaper than current mass-produced thin film and silicon based modules – and hastening the charge towards grid parity for solar PV.

First Solar, currently the world’s largest thin film solar PV module manufacturer, had predicted reaching 40c/W by 2017 through increases in efficiency. RSI says it can deliver that cost in 2014 by doubling the size of the module through a process known as Rapid Efficient Electroplating on Large- areas (REEL).

The company is backed by a group of venture capital firms, including the CalCEF Clean Energy Angel Fund co-managed by Australian Paul Fox, as well as Silicon Valley powerhouse Mayfield Fund, greentech VC specialist Nth Power, and Vancouver-based Pangaea.

Fox told RenewEconomy that the technology breakthrough would hasten the march towards grid parity for solar PV.

“The significance is that we can now deliver 40c/W, and will do so in 2014. People didn’t expect that to happen until 2017. This is a real acceleration. It is a step change in cost structure of PV. We are heading  owards wholesale grid parity several years earlier than expected.”

The next step for the firm is to strike licensee exclusive agreements with manufacturers in each major region of the world. The plan is for the first production to take place in 2014.

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According to RSI, the size of CdTe modules (pictured) has been limited by the use of high temperature CdTe deposition processes.  RSI says the REEL process speeds the plating step and eliminates constraints on panel area.

“The math is simple for large-area modules”, said RSI Co-founder and President Kurt Weiner. “At each step in the manufacturing process we are moving more Watts for a given capex, materials and labor cost.

“At the end, our panels produce significantly more power so they’re cheaper to install.

“When we founded the company we recognized   that in thin-film, you needed larger panel sizes with higher power outputs, in    addition to efficiency, to truly differentiate against silicon. We’ve achieved both at RSI.”

RSI CEO Ed Grady said incremental improvements to “undifferentiated technology” like crystalline silicon are not enough to prosper in this commoditised market.

“Manufacturers end up giving away their margin to survive,” he said. “First Solar has shown how to make profits through technology and cost differentiation. RSI is delivering a step change improvement in the cost structure, while retaining all the characteristics that have made CdTe so successful.”

Matt Jones, from Nth Power, said RSI had the highest potential of profit and investor return of any solar module the VC firm had seen. His optimism was shared by Pedram Mokrian from Mayfield.  

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  • George Michaelson

    cadmium is pretty nasty. and, its a byproduct of zinc and lead mining. So I can see a downside (high toxicity) and an upside (lead is pretty ubiquitous, lead mine waste is abundent, eg broken hill..)

    • Vic

      This is one of the many reasons I choose not to eat solar panels.

    • Bob_Wallace

      Sodium and hydrogen are problematic. Combined with chloride sodium makes table salt. Combined with oxygen hydrogen makes water.

      CdTe is something different than pure Cd.

      • George Michaelson

        how do you think they get the cadmium to make the cells? getting it from lead waste would be a net positive if it means its low impact. btw, did you do a toxicity check on CdTE? its a known issue that its going to have disposal consequences.

        • Bob_Wallace

          I’m not a materials scientist, George. I look to the findings of those who are….

          “The U.S. CdTe PV industry is vigilant in preventing health risks and has established proactive programs in industrial hygiene and environmental control. Workers’ exposure to cadmium compounds in PV manufacturing facilities is controlled by rigorous industrial hygiene practices and is monitored by frequent medical tests. Results of years of biomonitoring have shown that there are no significant observed increases in levels of worker exposure [2].”

          “Toxic compounds cannot cause any adverse health effects unless they enter the human body in harmful doses. The only pathways by which people might be exposed to PV compounds from a finished module are by accidentally ingesting flakes or dust particles, or inhaling dust and fumes.

          The thin CdTe/CdS layers are stable and solid and are encapsulated between thick layers of glass. Unless the module is purposely ground to a fine dust, dust particles cannot be generated. The vapor pressure of CdTe at ambient conditions is zero. Therefore, it is impossible for any vapors or dust to be generated when using PV modules. ”

          “The flame temperatures in typical U.S. residential fires are not high enough to vaporize CdTe; flame temperatures in roof fires are in the 800o–900oC range, and, in basement rooms, in the 900o–1000oC range [9]. The melting point of CdTe is 1041oC, and evaporation starts at 1050 oC. Sublimation occurs at lower temperatures, but the vapor pressure of CdTe at 800C is only 2.5 torr (0.003 atm). The melting point of CdS is 1750oC, and its vapor pressure due to sublimation is only 0.1 torr at 800oC.

          Preliminary studies at Brookhaven [10] and at the GSF Institute of Chemical Ecology in Germany [11] showed that CdTe releases are unlikely to occur during residential fires or during accidental breakage. The thin layers of CdTe and CdS are sandwiched between glass plates; at typical flame temperatures (800o–1000°C), these compounds would be encapsulated inside the molten glass so that any Cd vapor emissions would be unlikely. In any case, the fire itself and other sources of emissions within the burning structure are expected to pose an incomparably greater hazard than any potential Cd emissions from PV systems.”

          http://www.nrel.gov/docs/fy03osti/33561.pdf

          • George Michaelson

            Nice report. Thanks Bob. Suggests there was some concern to be addressed, beyond the facetious table salt comment, no? I doubt they would have addressed the problem if the materials didn’t pose risks. They also mention the cadmium is primarily in the US stockpile as a result of zinc mining and exists anyway. Gosh. That’s kind of the other half of my original comment, can we use post mining waste?

            I hope the process can consume post mine waste like the lead rich ore/dust at Mt Isa for two reasons: we might as well use what we’ve got, and it might mean we get to add value into the PV supply chain here in Australia. Getting to nine 9s purity is usually about zone refined crystallization but that’s a long way downstream of other industrial processes and I suspected (without evidence) the reports don’t address that part. These guys obviously did question the whole life cycle and again, it isn’t exactly a ‘nothing to see here’ situation. The cells have low risks, but whole of life issues have to be addressed.

  • Nick Sharp

    Tellurium is extremely rare. Wikipedia says it has “an abundance in the Earth’s crust comparable to that of platinum”. I guess it is used in these PV cells as a minute amount of “doping” material, but even so, its ‘abundance’ might be an issue.

    Would old cells (if they do wear out) allow relatively easy recovery of Te? We must begin to take an asset view of non-renewables, instead of regarding them as consumables. And check the global inventory of the rarer ones before assuming the latest technofix will be the saviour of our lifestyle. Some might. Some won’t.

  • David Kunhardt

    How do I, as a solar provider, assure my host customer that I am not introducing hazardous waste onto their property? How do I sign loan documents assuring the same? When I sign non-recourse loan documents that have a recourse carve-out for environmental hazards, what do I tell my stockholders about the environmental risks they retain?
    David

    • Bob_Wallace

      By learning some basic chemistry.

      And, even easier, checking to see what government safety agencies have to say. For example…

      “A byproduct of mining, Sinha explained, cadmium is highly toxic and carcinogenic. Exposure can cause lung, kidney or liver pathology or failure. In the presence of tellurium, however, cadmium forms a crystalline lattice that is highly stable (high boiling point, low vapor pressure, low solubility). “It likes to be a solid,” Dr. Sinha said. “It is several orders of magnitude — a factor of 100 — less toxic than cadmium.”

      CdTe is still a potentially toxic material. But the way it is encapsulated in glass in First Solar panels, Sinha said, sharply limits the possibility of inhalation or ingestion exposure.

      “The semiconductor material is bonded to a sheet of glass under very high temperature,” Sinha explained. “An industrial laminate material, ethyl vinyl acetate, a type of plastic, encapsulates the semiconductor and seals it between a second piece of glass.”

      Freeing the CdTe from the laminate is the biggest challenge of recycling, Sinha said. It would take a very rare and daunting set of circumstances to both free the CdTe and release cadmium.”

      http://www.greentechmedia.com/articles/read/how-safe-is-first-solars-cdte-thin-film

      and –

      “The U.S. CdTe PV industry is vigilant in preventing health risks and has established proactive programs in industrial hygiene and environmental control. Workers’ exposure to cadmium compounds in PV manufacturing facilities is controlled by rigorous industrial hygiene practices and is monitored by frequent medical tests. Results of years of biomonitoring have shown that there are no significant observed increases in levels of worker exposure [2].”

      Toxic compounds cannot cause any adverse health effects unless they enter the human body in harmful doses. The only pathways by which people might be exposed to PV compounds from a finished module are by accidentally ingesting flakes or dust particles, or inhaling dust and fumes.

      The thin CdTe/CdS layers are stable and solid and are encapsulated between thick layers of glass. Unless the module is purposely ground to a fine dust, dust particles cannot be generated. The vapor pressure of CdTe at ambient conditions is zero. Therefore, it is impossible for any vapors or dust to be generated when using PV modules. ”

      “The flame temperatures in typical U.S. residential fires are not high enough to vaporize CdTe; flame temperatures in roof fires are in the 800o–900oC range, and, in basement rooms, in the 900o–1000oC range [9]. The melting point of CdTe is 1041oC, and evaporation starts at 1050 oC. Sublimation occurs at lower temperatures, but the vapor pressure of CdTe at 800C is only 2.5 torr (0.003 atm). The melting point of CdS is 1750oC, and its vapor pressure due to sublimation is only 0.1 torr at 800oC.”

      Preliminary studies at Brookhaven [10] and at the GSF Institute of Chemical Ecology in Germany [11] showed that CdTe releases are unlikely to occur during residential fires or during accidental breakage. The thin layers of CdTe and CdS are sandwiched between glass plates; at typical flame temperatures (800o–1000°C), these compounds would be encapsulated inside the molten glass so that any Cd vapor emissions would be unlikely. In any case, the fire itself and other sources of emissions within the burning structure are expected to pose an incomparably greater hazard than any potential Cd emissions from PV systems.”

      http://www.nrel.gov/docs/fy03osti/33561.pdf

  • rarnedsoum

    A big concern, not addressed in this advertorial article, is lifetime degradation. Thin film degrades much faster than C-Si.
    C-Si will still produce as much as 90% of its original rated power at the end of 25 years. What will CdTe produce then?
    $/W is an outdated metric. LCOE is the intelligent way to invest in solar, whether you are residential or a bankable project.

    • Bob_Wallace

      Where are you getting your data for thin film degrading much faster than C-Si?

      $/W is a meaningful statistic. It gives the ability to compare panel cost and installed system prices without capacity. LCOE if you’re looking at the cost of electricity in a particular location. Better yet, total LCOE which includes the cost of transmission.