With solar energy systems growing in popularity and adoption across the globe, methods for enhancing the efficiency and power density of solar cells are a hot topic for renewable energy research labs. Essentially all photovoltaic technologies currently available suffer from reduced efficiency when operating at higher than nominal temperatures. In an attempt to reduce the operating temperature of solar cells, a group comprised of researchers from the UK and India, have explored a combined passive cooling solution, which incorporates micro-fins, phase change materials (PCM), and nanomaterial enhanced PCM (n-PCM) technologies. 3-D printed components for PCM containment were also analyzed for their performance compared to traditional machined and fastener-assembled parts.
The research group fashioned a test system for the compliment of passive thermal management solutions from a reduced-scale thermal system with electric heaters replacing the photovoltaic cells. Using electric heaters instead of photovoltaic cells likely allowed for a more controlled experimental setup with greater accuracy when comparing the various thermal management solutions. An un-fnned metallic plate was first used as a control, and the performance of a micro-finned plate under natural convection conditions. Then, the PCM and n-PCM systems were added to the un-finned and micro-finned metallic plates to compare the effectiveness of the combined system.
It was found that the average temperature in the center of the system was dropped by 9.6 ℃ using the PCM with the un-finned metallic plate, and 11.2 ℃ using the n-PCM and un-finned metallic plate. Comparatively, the performance of the combined thermal management system was enhanced by the micro-finned metallic plate with a reduction of 10.7 ℃ with the PCM and 12.5 ℃ with the n-PCM. Moreover, it was discovered that the 3-D printed PCM containment enhanced the leakage control of the system compared to traditionally manufactured containment. Lastly, the PCM and n-PCM materials were analyzed with a Differential Scanning Calorimeter to deduce their respective thermophysical properties.
The findings of this research may lead to enhanced performance building-integrated concentrated photovoltaic (BICPV) systems, even though the results may not seem dramatically significant. Even a slight improvement of photovoltaic efficiency could lead to gigawatts of additional solar energy production with only a 10 ℃ decrease in the average operating temperature of BICPV. Also, solar cell life spans may also be lengthened with a reduced operating temperature, and failures due to thermal degradation may also be reduced.
S. Sharma, L. Micheli, A.A. Tahir, and T.K. Mallick from the Environmental and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9FE, UK.
W. Chang from the Centre for Precision Manufacturing, University of Strathclyde, Glasgow G1 1XQ, UK
K.S. Reddy from the Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India