Stion, a startup that's been in stealth mode since its founding in 2006, is coming out of its shell.
The company will likely release its first product -- a copper indium gallium selenide (CIGS) solar module -- in June, said CEO Chet Farris in an interview. Stion currently is in the final stages of certification for its CIGS module. It will then follow up in 2011 with a module made of two separate modules mechanically sandwiched together: one of Stion's CIGS panels and another from the company made of solar cells containing chalcopyrite.
The idea behind the tandem module is that the CIGS layer and the more unusual layer can harvest energy from different ranges of the spectrum of light. Ideally, this will let the combined panel produce more energy consistently during a single day.
Prototypes of the tandem cell have an efficiency of around 15 percent, while the CIGS cells have a circuit efficiency of around 13 percent.
Stion, he added, will also produce its panels largely on industry-standard equipment. One tool for making the CIGS panel and one tool for making the other cells has been customized, but everything else basically comes from the basic lines of equipment makers, which lowers manufacturing costs.
"We've always had this pursuit of a tandem," he said. The modules are on glass substrates.
At volume manufacturing levels, Stion will produce CIGS and tandem junction modules for less than $1 a watt, he added. The low price comes in part from the manufacturing equipment strategy, as well as from the design of its CIGS modules. The cells in the module do not have to be strung together independently.
"From a capex point of view, it will be less than a dollar per watt," Farris said.
Will 2010 be the long awaited year of CIGS? Maybe. Global Solar, Solyndra and Miasole are already producing panels for commercial production. Global has a total manufacturing capacity at two sites of around 75 megawatts, and tests conducted by NREL on Global's CIGS modules on a flexible stainless steel substrate showed that the units exceed 13 percent efficiency. Ascent Solar Technologies, meanwhile, said it has begun to manufacture CIGS modules on flexible substrates with a 10.5 efficiency.
Stion has a small manufacturing facility that can produce 5 megawatts of cells a year. The units to be derived from the first round of production are already committed to customers. The company will expand to 10 megawatts and later, of course, will try to move beyond that if all goes well. Stion initially will focus on commercial customers and later target utilities for large-scale solar farms when factory capacity increases.
Globally, the solar industry produced 8.95 gigawatts of solar modules in 2009, according to Shyam Mehta of GTM Research, so the total CIGS production remains a drop in the bucket. CIGS proponents, however, claim they will expand production and will be able to undercut the cost of crystalline silicon modules -- which now sell for around $1.75 to $1.50 a watt -- while beating the efficiency of other thin films like cadmium telluride or amorphous silicon. Cad-tel solar modules hover around 11 percent efficiency, while amorphous silicon solar cells hit around 7 percent efficiency. Some tandem amorphous cells can achieve around a ten percent efficiency, with a cost that will approach 70 cents a watt in the relatively near future. NREL has produced some CIGS cells exhibiting an efficiency of more than 19 percent.
CIGS has been held back by the difficulty of moving toward mass manufacturing: getting those four elements to work together is like organizing a Van Halen reunion. Nearly every manufacturer uses a different process and many have had to customize their equipment as a result. Nanosolar relies on a printing process, while Miasole uses a sputtering process that has its roots in the hard drive business. Solopower,on the other hand, applies the materials with electroplating, while Stion employs a two-stage sputtering process.
Although many CIGS companies now seem to have a handle on manufacturing issues, they also face a very different market than when many started in the mid-90s, a period when silicon remained in short supply. Now, solar manufacturing capacity exceeds demand, a global economic crash has made investors skittish and Chinese manufacturers have relentlessly driven down the cost of crystalline silicon panels. Whether they can overcome these real-world hurdles remains an open question. Back in 2008, Stion said it aimed to produce modules in 2011 for around $3 a watt -- the company clearly has had to adapt to a different world.
Farris, however, points out that Stion has gotten this far with only $44 million -- $34 million from investors and $10 million in debt. Other CIGS vendors have raised hundreds of millions of dollars.
Rumors have floated for years about Stion's exact formula. Many have speculated that the company was working on quantum dot solar cells (which sources close to the company have denied in the past) or solar modules that combined CIGS and amorphous silicon. In the past, the company has even denied that its panels would be CIGS-based. Technically, if you think of the tandem product as Stion's signature offering, that's true.
"It is not silicon based. It is not cadmium telluride. It is not CIGS," said Frank Yang, manager of business development, told me in 2007. "In due time, we will make [the product's composition] publicly available."
"We have a number of materials in our toolbox, some of which we are using for the current products and others of which we will deploy in the future," Farris said. "We are a materials-agnostic company in that our plan has always been to manufacture high-efficiency, low-cost thin-film products using commercially scalable materials and processes, and we focus on solutions which fit those criteria."