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German CIS/CIGS with a Chinese accent: Odersun joins forces with AT&M to produce thin-film PV

06 November 2009 | By Tom Cheyney | Chip Shots

The companies’ relationship has reached a new level of cooperation with the announcement of the formation of a joint venture in the Chinese capital where the German’s proprietary CIS cells and modules will be manufactured and innovated with an eye on the nascent Chinese building-integrated PV sector. This edition of the blog discusses Odersun's unique technology and provides exclusive additional details on the JV with its Chinese partner.

Although plenty of companies developing and manufacturing copper-indium-(di)sulfide/copper-indium-gallium-(di)selenide (CIS/CIGS) thin-film PV have chosen to use flexible materials as their substrates of choice, only one employs copper metal tape--Odersun.

The German company was founded in 2002 with government funding after years of development work at the Frankfurt Institute for Solar Technology. It received initial investor funds in 2006 and opened SunOne, its first 5MW line, in Frankfurt (Oder) in 2007. After more Series B funding and the procurement of a bridge loan, Odersun started building out its second production site, SunTwo, a four-line, 20MW facility in Fürstenwalde (Spree), which has tools installed and commissioned, and should be finished and certified by the end of 2009, according to CEO Hein van der Zeeuw.
odersun_produc1

Chinese firm Advanced Technology & Materials has been along for the ride with Odersun as a strategic investor and research partner since 2004. The two joined forces to design, build, and install a special glass-module CIS PV system for a parking structure adjacent to the famous “Bird’s Nest” stadium as part of the Beijing Olympics (see photo at bottom of column).

The companies’ relationship has reached a new level of cooperation with the announcement of the formation of a joint venture in the Chinese capital, where the German’s proprietary CIS cells and modules will be manufactured and innovated with an eye on the nascent Chinese building-integrated PV sector.

I’ll get back to the AT&M JV news later in the blog, but first here’s more background on Odersun. I met with Van der Zeeuw at the recent EU PVSEC event, where the former NXP Semiconductor exec briefed me on the company’s history and technology and then updated me on its progress.

He explained that Odersun processes its CIS cells on kilometer-long rolls of 1cm-wide strips of copper film on a roll-to-roll (actually reel-to-reel) production line composed of custom toolsets, then winds the film up on big spindle-wheels. Aside from the unusual substrate material, the company’s process flow has some other differences from most other CIS/CIGS, including the lack of the usual molybdenum back-contact film (good golly, no Moly!). Odersun cleans the copper tape, then deposits the indium straightaway.

After the sulfurous element of the absorber layer is formed, the cells go through etch and annealing processes, before taking the usual cadmium sulfide buffer-layer bath and then getting sputtered with a zinc-oxide TCO (the only vacuum process in the whole sequence, according to Van der Zeeuw).
The final process steps involve backside cleaning, edge and shunt passivation, edge rubber, edge isolation, and backside isolation steps, after which the copper cells must pass a final online quality control check. Once okayed, the long strips are then wound onto what the company calls “CISCuT reels,” he said.

odersun_supercells The copper strips are rolled off those reels at captive or external moduling lines, where the film is then cut, overlapped, and interconnected in the width and length desired and connected to form “supercells” (shown at left), which can be assembled during final packaging into various dimensional configurations for glass panels, glass-foil laminate, or other customized flexible BIPV products.

The company’s first product, which will start shipping in the first quarter of 2010, is a framed standard module with five supercell strings, the CEO said. The company sees the benefit of taking a standardized path to market at first, so it can learn to produce a simpler product before moving on to markets where more customized solutions will be offered.

As for flexible modules, Van der Zeeuw cites the usual challenge facing the sector—developing and perfecting a reliable, long-living, low-cost barrier encapsulation material set. “We’re not there yet, but it is possible,” he said, noting the company’s and other R&D efforts in that area. In fact, after our meeting he was off to talk to 3M about that very issue.

Odersun has some work to do in the conversion efficiency area, since current series-production line efficiencies of the cells are about 7% (champion cells have hit 11%), according to the CEO, with a medium-term goal of hitting cell efficiencies of better than 12%. He believes there’s “lots of headroom within four years” to get the modules to efficiencies “well over 10%.”

Process and tool optimization in the new fab as well as an upgraded inline process control system should help drive up median efficiencies, although some industry experts wonder if the company can achieve those double-digit efficiencies without eventually changing its process recipe and introducing selenium into the absorber film stack.

Now back to the AT&M JV news. I emailed Odersun earlier this week with follow-up questions about the intriguing venture, and Van der Zeeuw responded with more details (through corporate communication liaison Korinna Penndorf).

The new entity has “no official name yet, but we are working on it,” he said. The financial arrangement consists of an “initial proportional distribution of 25% Odersun/75% AT&M in the JV, and plans are to invest about €80 million. The contract is about 50 years. Since AT&M has been a partner of Odersun since 2004, the idea of a joint venture has been there before. However, talks for this JV only began in 2009.”

As for the Chinese facilities being planned, they “will have a capacity of 20MW at first, expanding to 120MW in the following years,” he related. “Initially it will surely be Odersun’s suppliers equipping the JV’s facilities, nevertheless this does not exclude the possibility to move on to Chinese suppliers as well. Our German facilities are the model for the JV’s facilities in China.”

odersun “It will include both cell manufacturing and “supercell” stringing/module manufacturing,” Van der Zeeuw (pictured at left) continued. “We will do a ‘smart copy’ of our German production lines. At this early stage we cannot give much more details on construction or ramp-up.”

He said that construction is set to begin in 2010 and first products scheduled for shipment in 2011; however, the site of the new fab is still being discussed. “AT&M has an existing site available, but we are still examining the possibilities.” The companies will also cooperate on R&D efforts.

Van der Zeuuw made clear that the timing of Odersun’s German expansion plans will not be “affected by our commitment in China. The plan is still to extend SunTwo to its full capacity and to start with SunThree [a planned 30MW fab] in Germany in 2011.”

Despite the potential upside of Odersun’s unique CIS technology as well as the JV with AT&M and resulting access to the ballistic Chinese market, several rather large elephants are sitting in the room.

Can the German company get its production costs down, its efficiencies and yields up, and its products certified for long-term reliability (and how much help can AT&M offer in those areas)?

Will the market be ready for the flex CIS wares, when and if they are primed for volume production?

And will the new partnership, one of the small but growing number of Chinese and non-Chinese PV companies joining forces on Chinese soil, be a successful litmus test for the viability of such well-meaning but admittedly risky alliances--or not?