| Work Detail |
The Chinese Academy of Sciences has developed a new technique that uses non-toxic limonene as a reagent to control the degree of expansion of EVA during the decapsulation process of out-of-use photovoltaic modules. The proposed method achieves complete delamination of the glass and backsheet without excessive damage to the solar cells.
A group of scientists led by the Chinese Academy of Sciences (CAS) has developed a new method to remove ethyl vinyl acetate (EVA) from solar modules at the end of their life cycle.
“Our research indicates that controlling the degree of expansion of EVA is crucial for effective delamination,” lead author of the research Dong Wang told pv magazine . “Based on this, we carefully selected natural limonene as an environmentally friendly solvent. At certain concentrations and temperatures, limonene can induce proper expansion of EVA, effectively breaking interface bonds without causing excessive expansion and damaging solar cells. This process allows the complete delamination of the glass.”
Limonene is a chemical found in the peel of citrus fruits, such as lemons, limes and oranges, and according to the research team, it facilitates the controlled swelling of EVA in the delamination process, which in turn prevents rupture. of cells due to uneven force during swelling.
“This reagent does not react chemically with EVA, which mainly induces the controllable swelling of EVA, creating the conditions for efficient recycling of the reagent,” Wang further explained, adding that this non-toxic reagent achieves interlayer separation through disruption. of the silane groups on the surface of the glass and the backsheet in contact with the EVA.
The scientists conducted a series of experimental tests in a double-layer glass reactor and a constant temperature ultrasonic reactor to generate ultrasonic physical fields. The glass separation rate was determined by the weighing method, which consists of measuring the mass of the glass before and after separation with an electronic balance.
They also used thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) to analyze the chemical composition and bonding mechanism at the interface between EVA, glass, solar cells and backsheet.
The analysis showed that the new technique is supposedly capable of breaking the bonds in the interfacial adhesive region without excessively damaging the solar cells. “This controlled swelling proved to be essential for effective delamination, as evidenced by the degree of swelling and morphological changes,” the academics stated.
“Under optimized experimental conditions, we were able to completely separate the glass and the backsheet, enabling full potential recovery of the crystalline silicon solar cells,” added Wang, noting that adjusting the concentration of the limonene solution was the key. key to effectively regulate the expansion of EVA. “By combining it with the physical field of ultrasound, we accelerate the penetration of the solvent and the breaking of the cross-links, thus improving the efficiency of the separation.”
The research team presented the method proposed in the study “ Effective decapsulation method for photovoltaic modules: Limonene-induced EVA controlled swelling under sonication and debonding mechanism analysis ” and analysis of the debonding mechanism), published in the Journal of Cleaner Production . |
