What is it about?

Solar panels convert sunlight into electricity, but their performance can decrease as they become hotter. This study investigates an approach that cools photovoltaic panels while also recovering useful heat. The researchers developed a photovoltaic-thermal (PV/T) collector in which a water-based cooling fluid containing graphene nanoplatelets circulates through a serpentine copper tube installed behind the panel. Two graphene concentrations, 0.05% and 0.1% by mass, were experimentally tested and compared with a conventional reference photovoltaic module. The results showed that the cooling system reduced the panel temperature by approximately 9% and 14%, respectively. Electrical power output increased by 38.31% with the 0.05% nanofluid and by 48.74% with the 0.1% nanofluid compared with the reference module. The PV/T collector also recovered heat from the panel. The average thermal power obtained was 37.20 W at the lower graphene concentration and 57.91 W at the higher concentration. The highest overall energy efficiency, 50.89%, and exergy efficiency, 13.6%, were achieved with the 0.1% graphene-based nanofluid. The findings demonstrate the potential of combining photovoltaic cooling with heat recovery to make better use of solar energy. The study also examines a circulation system powered by solar energy, reducing its dependence on electricity from the grid.

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Why is it important?

Photovoltaic systems generally convert only part of the incoming solar energy into electricity, while a considerable portion is dissipated as heat. Recovering this thermal energy while reducing panel temperature offers an opportunity to improve overall solar energy utilization. This study experimentally demonstrates that graphene nanoplatelet/water nanofluids can support both cooling and heat recovery in a PV/T collector. The 0.1 mass% concentration achieved the highest electrical output, thermal power recovery, and overall energy and exergy efficiencies among the tested configurations. Another important aspect is the use of a solar-powered circulation system, which reduces dependence on grid electricity for operating the cooling equipment. The environmental-economic assessment also explores the potential emission-reduction benefits of improved solar energy utilization. These results provide experimental evidence for further development of nanofluid-based PV/T systems, while long-term fluid stability and possible corrosion effects remain important topics for future research.

Perspectives

From my perspective, this study is valuable because it addresses two important aspects of photovoltaic technology simultaneously: improving electrical performance through cooling and recovering thermal energy that would otherwise be wasted. I find the use of graphene nanoplatelet/water nanofluids particularly interesting because even low nanoparticle concentrations can provide meaningful improvements in the tested PV/T configuration. Another important aspect is the integration of a solar-powered circulation system, which supports the aim of reducing the system's dependence on external electricity. I believe that energy and exergy analyses are essential for understanding not only how much energy a system produces, but also how effectively it utilizes the available solar resource. Future research should investigate long-term nanofluid stability, material compatibility, and system performance under different climatic conditions.

Assoc Prof Selcuk Selimli
Karabuk Universitesi

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This page is a summary of: Energy and exergy conditioning of graphene nanoplatelet/water nanofluid circulatory cooled photovoltaic thermal collector, Journal of Thermal Analysis and Calorimetry, April 2026, Springer Science + Business Media,
DOI: 10.1007/s10973-026-15444-0.
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