Scientists in China developed a novel swelling process to detach glass and EVA backsheets from solar modules at the end of their lifecycle. The technique utilizes an ester of a dicarboxylic acid known as dibasic ester. It reportedly prevents excessive cracking of solar cells.
A research group from the Chinese Academy of Sciences, and China-based solar panel maker JinkoSolar, have developed a new swelling process to separate glass and backsheets based on ethylene-vinyl acetate (EVA) from solar cells in end-of-life modules.
“Our swelling process is not violent and controllable,” said Wang Dong, the research’s lead author. “It doesn’t break the solar cells and ensures high-efficiency recycling rate of the cells and precious metals. Furthermore, it has a very low toxicity and the swelling agent can be recycled.”
In the paper “Recycling of solar cells from photovoltaic modules via an environmentally friendly and controllable swelling process by using dibasic ester,” published in Clean Technologies and Environmental Policies, the scientists explained that the process uses a dibasic ester (DEB), which is an ester of a dicarboxylic acid commonly used as lubricant, spin finish, and additive.
“DBE is a promising green solvent widely used in the coating industry that is a mixed ester composed of dimethyl succinate, dimethyl glutarate, and dimethyl adipate,” they said. “In addition, DBE has a boiling range of 196 C to 225 C and can dissolve most resins.”
The DBE is claimed to penetrate into the glass-EVA gap effectively while preventing moisture in the air from entering the separation system to hydrolyze DBE. In the next step, an ultrasonic field is used to promote the separation of glass-EVA.