Building Better Solar Cells, at Robot Speed

Testing out new types of solar cells at the National Renewable Energy Laboratory's Process Development and Integration Lab used to involve multiple rooms, numerous pieces of equipment and any number of possible sources of error or accident. Enter a robot.

The lab now has several robotic bays that have automated the process of making new solar cells with varying base components, streamlining the process to an extreme degree. It's also a lot faster than it used to be. According to a story posted on the NREL website:

"How much faster? The robot working with silicon can build a semi-conductor on a six-inch-square plate of glass, plastic or flexible metal in about 35 minutes. It pivots and dishes like a point guard, sifts like a master chef, analyzes like a forensics expert and does it all while maintaining a vacuum seal on the entire process."

There are other robots as well, with two of them specializing in different materials. One uses Copper Indium Gallium diSelenide (CIGS) and another that has yet to be brought online uses cadmium-telluride.

The ongoing goal of improving solar cells is to bring their cost into a range that would be competitive with traditional power generation sources. Solar technology companies working toward that goal will now be able to use the NREL robot army to rapidly speed up testing of new materials and formulas for their cells. A big part of that cost equation is raising the percentage of the sun's energy hitting the cell that can be converted into electricity. Several years ago at NREL, researchers set a record by achieving 40.8 percent efficiency; most rooftop solar cells come in at around 11 or 12 percent.

"The system was designed to allow us to do things we could not do before, such as get a better look at impurities and the quality of materials, the different layers that compose the CIGS cell," said Miguel Contreras, a senior scientist at NREL. "It's helping us understand better what is limiting our efficiencies, as well as learning how to improve industrial productivity."

Images via NREL.

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