Recycling process promises ‘better than new’ silicon wafers

Scientists in China have developed a new recycling process for PV modules that can recover intact silicon cells from end-of-life products, and process them back into wafers. As part of the recycling process, the wafers are purified and surface-treated, making them suitable for integration into new, high-efficiency cells and modules.

A new process to recover wafers could dramatically cut the energy cost required to produce recycled silicon cells.

Image: Ministère de la Transition écologique

With this in mind, the group sought ways to recover silicon wafers suitable for production of high efficiency cells and modules. They demonstrated a series of chemical treatments that are shown to both purify wafers and improve their surface characteristics, making them suitable for use in new, high-efficiency cells. The process is described in full in “A systematically integrated recycling and upgrading technology for waste crystalline silicon photovoltaic module,” which was recently published in Resources, Conservation and Recycling.

The group took advantage of a process previously used by wafer manufacturers to reduce surface reflectivity and produce “black silicon” wafers.

“Through this technology, desirable and highly pure Si wafers with intact structure, minimally reduced thickness and excellent light-trapping ability are successfully obtained,” the group explained. “The properties of the reclaimed Si wafers are characterized and evaluated for new solar cell manufacturing and packaging, which encourages regenerated solar cells with higher power conversion efficiency than that of new commercial solar cells.”