New technique restores healthy PV cells in aging panels

They discovered an effective, cheap and environmentally friendly alternative to restore healthy photovoltaic cells from aging solar panels (photo: CC0 Public Domain)

Researchers from the Chinese Academy of Sciences and Chinese solar panel manufacturer JinkoSolar have developed a new process to separate healthy photovoltaic cells from solar panels at the end of their useful life.

The technique is based on something scientists call “swelling” achieved through a chemical reaction. “Our process does not destroy the solar cells and provides a highly efficient recycling rate of the cells and precious metals,” said Wang Dong, the lead author of the study. “Also, it has very low toxicity and the swelling agent can be recycled.”

In an article published in Clean Technologies and Environmental Policies, the scientists explain that the process uses a dibasic ester (DBE), which is an ester of a dicarboxylic acid.

“DBE is a promising green solvent widely used in the coatings industry, which is a mixed ester composed of dimethyl succinate, dimethyl glutarate, and dimethyl adipate,” the scientists explain. “DBE has a boiling range of 196 C to 225 C and can dissolve most resins.”

The substance is said to effectively penetrate the gap between the glass and ethylene-vinyl acetate in solar panels, while preventing moisture in the air from entering the separation system. In the next step, an ultrasonic field is used to promote separation of the layers.

The scientists tested the new technique on a Jinko 535 W solar module measuring 1956×992 mm and weighing 22.5 kg, with the junction box and aluminum frame removed beforehand.

At the same time, the new process is also cheaper, the researchers point out, comparing it to a similar process based on another chemical, O-dichlorobenzene. The difference in the price of the two substances is almost double.

“In conclusion, the use of DBE to separate glass from ethylene-vinyl acetate can preserve the relative integrity of the latter to make resource recovery more manageable, and the use of DBE as a separation reagent has the advantages of low cost and protection of environment,” emphasizes Dong.

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