Solar Cells Info

Jan 14, 2008
Source: FabTech.Org
http://www.fabtech.org/content/view/5956/

Few solar photovoltaic sectors exhibit as volatile a combination of hype and promise as the copper indium gallium (di)selenide (CIGS) thin-film segment. A handful of companies–Global Solar, Wurth, Showa Shell, for example—are already manufacturing relatively modest amounts of commercial products using CIGS (or its cousin, CIS) films on glass, stainless steel, or flexible substrates, while a larger number are just developing (or trying to develop) processes, building and characterizing (or trying to build and characterize) pilot or initial manufacturing lines, or talking (and talking) about building volume-manufacturing facilities.

CIGS companies are a mix of public and private, venture-funded start-ups and units of large corporations, relative newbies and long-time veterans. Process technologies employed by the CIGS crowd, many of which have been in R&D for decades, range from vacuum to nonvacuum, evaporation/coevaporation to sputtering, ink-print to selenization, electrochemical to RTP diffusion techniques—or combinations thereof. Some use rigid substrates, others prefer flex, some employ batch process techniques, while others take a roll-to-roll or web approach. Module integration strategies include both discrete and monolithic approaches.

The CIGS players tout common themes on the advantages of modules made with their material: The thin-film cocktail has the most conversion-efficiency upside of any non-crystalline silicon PV material (up to the high teens, though current device efficiencies are in the low double-digits and module efficiencies a few percentage points below that). The toolsets are/will be cheaper and more efficient, and the process promotes better utilization of the critical materials, especially compared to c-Si technologies. CIGS provides the best opportunity for facilitating true building-integrated PV, which will be a huge market some day, and also will be very competitive for large, utility-scale solar farms and personal/portable apps. Most importantly, the delivered cost per watt of CIGS modules produced on fully characterized, volume CIGS lines will run less than a dollar–maybe even way less—thereby achieving the ultimate goal of grid parity with the existing carbon-generating power sources.

In recent months many CIGS outfits have made a series of PR and VC moves, while others have been quiet, even downright stealthy, or at least less prone to tooting their own horn. Honda Soltec created a bit of noise in mid-November when it opened its Kumamoto production plant, which it says will have a 27.5 MW capacity when fully ramped later this year. A week later, Solibro Solar, a spinoff from Angstrom Solar in Sweden and majority controlled by number-two solar-cell maker Q-Cells, said its first factory (25-30 MWp capacity) is under construction in Thalheim, Germany, and will come online in the second half of 2008. Global Solar announced in early 2007 that its second CIGS plant (30 MW) would open near Berlin in the latter half of this year, in addition to an expansion–from 4 to 40 MW—of its core Tucson fab. Showa Shell said last summer that it plans to add a 60-MW plant next to its current 20-MW CIS line in Miyazaki.

(Before continuing, a reality check: Even with the additional CIGS manufacturing capacity slated/alleged to be coming online this year and next, thin-film PV leader First Solar can already produce more than the equivalent amount of all near-term existing and projected CIGS megawattage on its cadmium telluride-on-glass production lines, and will vastly exceed the total worldwide CIGS capacity once its Malaysian factories start coming up to speed.)

Now back to CIGS…. Venture darlings Nanosolar and HelioVolt, no strangers to the media and investment community hype game, each sharpened their hand-waving skills in December. Nanosolar shipped the “world’s first printed thin-film solar cell in a commercial panel product” (and earned its first revenues) from its “fourth-generation” roll-to-roll line in San Jose. It also offered details of a 1-MW solar power plant in eastern Germany, to be integrated by Beck Energy, that will use the company’s panels. Many skeptics wonder how quickly (if ever) the company will ramp its production fab to its purported 430-MW ultimate capacity (which would place Nanosolar among the upper tier of solar manufacturers, at least in terms of production capabilities). But at least the magic words “shipped product” and “sales revenues” now appear on Nanosolar’s corporate resume.

As for HelioVolt, the company said it will use much of the record $101 million that it raised in Series B funding to start building and equipping its first plant near Austin, which will sport an initial production capacity of 20 MW, with first commercial products shipping by year’s end. The company also signed up leading MES supplier Eyelit as its manufacturing software infrastructure provider, which bodes well for HelioVolt’s ability to ramp its production quickly and effectively—as long as the company can dial its process in and scale it to volume.

In contrast to the more publicity-generating companies, Solyndra continues to operate in deep-stealth mode; its Website, little more than a help-wanted board, remains devoid of substantive information. Does the company really exist? How many people are working there? Who are the executives? What kind of CIGS process does it use? When will its fab be up and running and shipping product? Who are its customers? How is the company spending those tens of millions of venture investment funds? Even though being privately held means that Solyndra has no obligation to tell me or any other media or market types anything, I’d love to talk to the execs there, because this stealth stuff has become really stale, and they need to tell their story and let people know what they’re up to!

Although not strictly stealthy, SoloPower has been in silent running of late, with company CEO Houmayoun Talieh refusing interview requests from Chip Shots and other press outlets. The company did show up in the business press in early November, when the San Jose Business Journal reported that SoloPower will be moving its R&D and manufacturing operations from Milpitas to San Jose, thanks to cash and other incentives from the San Jose Redevelopment Agency. The move raises questions about whether the company will achieve its stated goal of having its 20-MW plant operational and producing commercial product by 3Q08. But that question (and others) will remain unanswered until Houmayoun or other company honchos decide to ‘fess up.

The fortunes of one-time sector darling Miasole came under scrutiny in late December, when the blogosphere helped break the story of layoffs of 40 employees at the Fremont, CA-based company as well as the departure of founder and former chairman, David Pearce. Both actions, as well as continued slippage in their production schedule, elicit concern about the dodginess of the company’s sputter-based, roll-to-roll CIGS processing and its ultimate commercial viability.

Making CIGS on foil in the R&D lab is one thing, but consistently producing devices on a production line, with high yields and competitive conversion efficiencies, is another, as Miasole has found out. DayStar Technologies, which like Miasole uses a sputter deposition process, has also discovered that production scaling of CIGS on foil is quite difficult. The materials don’t always cooperate when it comes to compositional control and uniformity. The publicly traded company announced last spring that it had switched from foil to glass modules for its initial product line (although it continues to work on developing the flexible steel). Still sticking to its “we’re building out our 25-MW production line” story, DayStar has offered few specifics of its manufacturing plans.

Later this week in Chip Shots, I will blog about a couple of CIGS purveyors that have taken a lower-key, less hyperbolic approach than some of their peers, but deserve to be a part of any substantive discussion on the current and future propects of thin-film PV : Ascent Solar and International Solar Electric Technology (ISET).

continued in part II