MIT’s Online Tool Tackles Solar Cell Impurity

It might come as a surprise, but the process of making a silicon solar cell isn’t actually that scientific. The process involves subjecting a thinly sliced wafer of silicon crystal to several stages of heating and cooling, using a delicate balance of intuition and experience. Fundamentally, it’s a matter of trial and error. But researchers at MIT (who, it seems, are always coming up with amazing cleantech innovations) have developed a simulation program that they say could help manufacturers of silicon solar cells make better solar cells more quickly, and with more certainty.

The research team, led by assistant professor of mechanical engineering Tonio Buonassisi, with collaborators from the Solar Energy Institute at Spain’s Technical University of Madrid, have developed a new online tool, called “Impurities to Efficiency” (I2E). I2E allows companies or researchers to plug in descriptions of their planned materials and processing steps, and spits out a simulation of the resulting solar cell’s efficiency in about one minute.

Cali Solar Solar Cells

image via NREL

Critical to I2E’s usefulness is its ability to predict exactly how iron atoms and particles will behave during the manufacturing process. Even though the silicon used in solar cells is 99.9999 percent pure, the tiny amount of iron particles that remain can block the flow of electrons.

David Fenning, a graduate student at MIT involved in the research, said that the size and distribution of the iron particles is very hard for manufacturers and researchers to both predict and measure. “There are a number of competing mechanisms that cloud the picture of exactly what is going on [in the wafer-making process],” he said. “It’s a constantly evolving problem. That’s what makes it interesting.”

Lauren Craig is a writer and consultant living in Seattle, WA. She holds an M.S. in International Development from Tulane University, and is co-founder of Sustainable Systems Integrators, LLC., an employee-owned solar energy design and installation firm in New Orleans, LA. She is also certified in PV design and installation by the North American Board of Certified Energy Practitioners (NABCEP).