Researchers at India's Centre for Materials for Electronics Technology (C-MET) have pioneered a new method for reclaiming lead (Pb) from end-of-life photovoltaic panels.

Lead, a hazardous component present in the soldering of copper ribbons within solar panels, is the primary focus of their recycling process. Duvvuri S. Prasad, the lead author of the study, highlighted the innovative nature of their approach, emphasizing its environmental consciousness and departure from conventional methods that prioritize the recovery of valuable materials. Instead, their process specifically targets lead, aiming for both environmental remediation and the creation of commercially viable lead monoxide (PbO).

The recovery process unfolds in three meticulously optimized steps. First, selective leaching of the top layer from interconnects is conducted using dilute nitric acid. This is followed by the extraction of lead from the resulting leachate through precipitation, achieved by altering the pH with an alkaline solution. Finally, lead is transformed into PbO through calcination at 500°C.

Prasad and his colleagues detailed these steps in their study titled "A novel approach for the efficient recovery of lead from End-of-Life Silicon Photovoltaic modules," recently published in Solar Energy Materials and Solar Cells. They emphasized the significance of each stage and the comprehensive analysis conducted using advanced characterization techniques to ensure effective lead recovery.

The researchers tested their approach on a 30 kg sample obtained from de-framed end-of-life polycrystalline silicon solar modules. The results were promising, yielding PbO with minimal impurities. The most efficient leaching of lead from interconnects was achieved using 1.5 M nitric acid at 60°C.

With an overall recovery rate of 70.45%, the recovered PbO holds potential for various applications, including lead storage acid batteries, pigment production for the paint industry, and applications in ceramics and glass industries.

Prasad highlighted the scalability of their process, validated through successful testing with a 200-gram sample. The recovered PbO, verified for phase purity using advanced characterization techniques such as XRD and SEM-EDS, opens avenues for diverse commercial applications. This innovative approach represents a significant step towards sustainable management of solar waste, offering both environmental benefits and economic opportunities.