Phoenix, AZ--Wakonda Technologies won't produce solar cells commercially for years, but if it can mature its process, the company says it could boost the performance of cadmium telluride panels.
Potentially, Wakonda could make cad tel cells with efficiencies in the high teens and sell panels at close to 75 cents a watt, said CEO Les Fritzemeier at the 2010 Solar Summit Sponsored by Greentech Media. The modules would be made on flexible substrates in a roll-to-roll process. Ideally, Wakonda would like to incorporate the solar cells into roofing materials. Currently, First Solar makes cells at around 85 cents a watt, but the efficiency comes to around 11 percent. First Solar's cells come on glass.
The key is the process. The company takes a sheet of copper and heats it to create a repeating grain pattern. The copper is then coated with another substance, which effectively becomes a mold of the pattern in the copper. The copper is then eliminated and active solar materials are added. Because of the shape of the second substrate, the solar materials take on the same pattern of the now-absent copper.
"The key to this is grain size," he said. The larger, the better.
It's similar to how ancient sculptors created statues with the lost wax process. The company calls it Virtual Single Crystal. Similar processes have been employed in chip making.
The process works with gallium arsenide, cadmium telluride and other materials, but Wakonda will concentrate on cad tel, said Fritzemeier. A market already exists for these products and the efficiencies can approach what can be accomplished with gallium arsenide. Wakonda will also try to license the process to lighting manufacturers to create flexible thin lights. Some have objected to the potential toxicity of cad tel, but the solar material is fully encapsulated, limiting the risk. (Arsenic is also an ingredient in gallium arsenide, he noted.)
Will it work? It's hard to say at this point -- many things from the lab don't make it into commercial production. One could also imagine semiconductor equipment manufacturers developing a similar process that doesn't necessarily touch on Wakonda's intellectual property.
But it again highlights that the cad tel field likely won't remain the private domain of First Solar. General Electric said last month that it will begin to produce cad tel panels next year with efficiencies that should rank among the highest in the industry. GE will exploit thin film expertise in its digital X-ray and OLED groups to develop the panels.
Abound Solar (formerly AVA Solar) has boosted the efficiency of its cad tel panels from 6 to 9 percent and is producing megawatt quantities of panels, said Tom Blaisdell of DCM, one of the company's investors, during a conversation in the hallway. Commercial installations of the product have already begun.