Researchers in India have developed a reusable tin-modified carbon nanotube gel that reduces solar cell operating temperatures by 9.5 C and improves power conversion efficiency. The gel maintained its cooling performance after 40 days of testing and could be reused following a simple water-soaking process.
Researchers in India have developed a reusable, thermally conductive gel that can passively cool silicon solar cells and improve their power conversion efficiency. The research aimed to develop a cost-effective and sustainable cooling solution that reduces operating temperatures, improves electrical performance, and extends the lifespan of photovoltaic devices without requiring external energy. The gel consists of polyvinyl alcohol (PVA) blended with tin (Sn)-coated and Sn-filled carbon nanotubes (Sn-CNTs).
“In the present study, Sn was employed as a coating material because of its excellent wettability, relatively low melting temperature (232 C), and good compatibility with carbon nano materials, enabling uniform coating of CNT surfaces,” the researchers explained. “Sn provides a practical balance of thermal performance, processability, interfacial compatibility, and economic feasibility, making it well-suited for enhancing the effective thermal conductivity of CNTs.”
To prepare the gel, the researchers dissolved 0.5 g of PVA in 5 ml of dimethyl sulfoxide at 120 C and added Sn-CNTs at concentrations of 0.5 wt%, 0.7 wt%, and 1.4 wt%. They stirred the mixtures for one hour and ultrasonicated them for 30 minutes before cooling and casting them into 5 cm × 5 cm molds. The samples were then kept at 0 C for 24 hours as part of a freeze-thaw crosslinking process. The team also prepared a pure PVA gel for comparison.
The scientists analyzed the gels’ structure and composition and measured their thermal conductivity, tensile strength, and thermal stability. For the cooling tests, they attached the 0.7 wt% and 1.4 wt% formulations to the rear of a commercial polycrystalline silicon solar cell and compared their performance with that of a device cooled with pure PVA gel and an uncooled reference device. They also monitored weight loss and device performance over 40 days. To assess reusability, they soaked the used 0.7 wt% gel in deionized water for 24 hours before testing it again.
“The intrinsic thermal conductivity of Sn-CNTs provides excellent heat transfer capability through the gel medium,” the researchers said. “Furthermore, PVA/Sn-CNT conducting gel manifested superior thermal conductivity of 3.2 W/mK and mechanical strength of 0.21 kPa. Consequently, the developed conducting gel highlights excellent potential for thermal management of solar cells without compromising the power conversion efficiency (PCE).”
The tests showed that the 0.7 wt% formulation reduced the solar cell’s operating temperature by 9.5 C and increased its power conversion efficiency from 12.5% to 13.2% under simulated sunlight. After 40 days, the gel-cooled device retained an efficiency of 12%, which increased to 13.3% after the gel was soaked in water and reused.
“Overall, this method offers a green, affordable pathway to boost solar efficiency, lifetime, and thermal control using sustainable materials,” the researchers concluded. However, the they did not provide a detailed cost assessment of the proposed cooling solution or compare its economic feasibility with that of existing solar cell cooling technologies.
The findings are presented in “Reusable thermally conductive Sn-CNTs infused PVA gel for efficient silicon solar cell module cooling,” published in Solar Energy. The research team included scientists from the Indian Institute of Technology (IIT) Mandi and Amity University in India.
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