When NuvoSun needs factory equipment, it goes to eBay.
The Palo Alto, Calif.-based startup – which wants to make copper indium gallium selenide (CIGS) solar cells on thin metal substrates – purchased one of its vacuum chambers in its prototyping facility from a military base through the auction site, said Dave Pearce, the CEO and founder. Another piece of production equipment was pieced together through components. One of NuvoSun's employees actually designed that machinery two decades ago so putting it together was somewhat straightforward.
The backyard ambiance in a lot of ways reflects the state of the solar union. Investors have plunked over $2.3 billion into CIGS companies alone. CIGS, though, accounts for less than 3 percent of the world solar market and most companies aren't even in production. Solar prices, meanwhile, have crashed. With a wave of acquisitions all but inevitable, cheap will be king.
"The days of free money in solar are gone, so you have to have a process that is more capital efficient," Pearce said. "You have to assume that $100 million is not available."
On the plus side, the past few years of CIGS experimentation and accumulated knowledge has made it easier to move quickly. The company was formed in January 2008. In July 2008, it had its first cell.
"It was 2 percent efficient," he said. "We said, 'Wow, it's photoactive.' "
Ten months later, it produced a small "champion" cell that exhibited 11.8 percent efficiency. That's in range of what other, more heavily funded CIGS companies have achieved. HelioVolt, which has raised $101 million, last year talked about efficiencies in the 10 to 12 percent range. Nanosolar, which has raised a few hundred million, has talked about producing 14.5 percent CIGS cells.
Ascent Solar, which makes novel CIGS-on-plastic modules, has hit 10.4 percent efficiency in a solar panel in its 1.5 megawatt pilot plant and produces panels with an 8 percent to 9 percent average efficiency.
Again, NuvoSun only produced a small test cell about the size of a thumbnail, and 11.8 percent efficiency is only a baseline achievement, but Pearce argues that it demonstrates that the company has come up with what could be a core of a workable manufacturing process.
"We're not trying to say we did a module. The important part is that we are delivering on viable reaction pathways," he said.
By the first half of next year, NuvoSun should be able to demonstrate a complete CIGS module exhibiting ten to 11 percent efficiency.
Technically speaking, CIGS has great promise. CIGS cells in labs have come close to 20 percent efficiency, or higher than the 16.5 percent efficiency of the best cadmium telluride lab cells. CIGS can also be deposited on foil, cheaper to process and transport than the glass substrates required for crystalline silicon or cadmium telluride cells. NuvoSun, in fact, will only make CIGS cells on sheet metal.
Mass producing CIGS modules, however, is sort of like trying to pull off a Van Halen reunion. The four elements do not work well together, which dampens efficiencies and lowers yields in mass production. Miasole, Pearce's first CIGS company, experienced both of those problems in trying to move to mass production. The company hopes to be in mass production next year. (Similarly, HelioVolt and SoloPower have swapped management teams and experienced delays.)
Pearce, for his part, agrees. CIGS makers will have to reduce their raw material costs for solar cells to 25 to 30 cents a watt. Finished modules will have to cost 70 to 75 cents a watt.
"Ultimately, modules will have to approach 50 cents a watt. At that, you can comfortably sell in the range of $1 a watt," Pearce said.
Not everyone is going to be able to do it. Some CIGS makers are talking about 30 and 40 megawatt factories that cost close to $100 million.
Efficiency will have to improve too.
"It is fairly straightforward to get to 10 to 11 percent, but you will separate the men from the boys when you go to 12, 13, 14 and 15 percent," he said. "It is deceptively simple to make small devices. The scaling has been the challenge."
So what is NuvoSun doing that might set it apart? The company has a precursor, post-selenization process that it combines with chemical plating. In this, the copper, indium and gallium are deposited in a fairly cold process. Selenium is added in a later high temperature process. Nanosolar has a two stage process that it combines with printing.
"The two-step process gives you more individual control. CIGS is all about determining the right reaction pathways," he said. "You can form all sorts of subspecies you don't want."
Some other companies use a reactive process in which all of the elements are added in a hot process. It's like trying to mix the cake batter and bake it all at the same time.