Researchers from India, Chile and Russia have developed a solar photovoltaic–thermal (PVT) system that uses hybrid graphene - carbon nanotube (CNT) nanoparticles in phase change materials (PCMs) to improve cooling and overall performance. The core idea is to turn the PCM layer into a much more conductive thermal “buffer”, so the PV cells stay cooler while more heat is usefully recovered.
Conventional silicon PV panels convert only about 10-12% of solar radiation into electricity, with the rest turning into heat that raises cell temperature and reduces power output by roughly 0.35% per °C above about 40 °C. PCMs such as stearic acid and paraffin wax can passively limit this temperature rise by absorbing excess heat as latent heat near the PV operating range, but their inherently low thermal conductivity slows heat diffusion and limits effectiveness. To overcome this, the researchers dispersed hybrid graphene - CNT nanoparticles (1:1 wt%) into stearic acid and paraffin wax at 2, 4, 6 and 8 wt%, creating hybrid nano‑PCMs (HNPCMs) with significantly improved internal heat conduction.
The nanocomposites were characterized by TGA, DSC and thermal conductivity measurements to confirm thermal stability, phase-change behavior and conductivity enhancement. When integrated into a working PVT collector, the best performance was obtained with stearic acid + 6 wt% hybrid nanoparticles: PV cell temperature dropped by 11 °C, the cooling water temperature rose by 12 °C, absolute electrical efficiency increased by 14.3%, thermal efficiency by 56.7%, and overall exergy loss decreased by 10.4% compared to a system without PCM.
These results show that an optimized graphene - CNT HNPCM can provide faster, more uniform heat spreading and more effective latent heat utilization, offering a practical route to higher efficiency and longer life for PVT systems in high-irradiance climates.
