A group of international researchers has examined how different designs affect the efficiency of photovoltaic-thermal (PVT) module efficiency.
The scientists modeled eight different types of PVT systems in software and compared them under the same conditions.
“This study aims to compare how well different designs of combined photovoltaic-thermal collectors work in electricity and heat production,” they said. “They were compared under conditions of a radiation of 1,000 W/m2, ambient temperature of 40 C, inlet water temperature of 45 C, and wind speed of 1m/s.”
Based on the first law of thermodynamics and numerical modeling in MATLAB, the academics designed eight models. Four of them were PVT collectors without glass cover and four were with glass cover. In each of those groups, the four thermal collectors were modeled with a spiral of round tubes or parallel rectangular tubes, parallel square tubes, and parallel round tubes. In all of the parallel settings, the module also had a metal sheet. Water was the working fluid in all cases.
To validate their modeling, the academic group measured its results against two 40 W PV modules they obtained. “The results show a good match between the parameters calculated in the present work and the experiments, and considering that the error in each test is less than 4%, the mathematical modeling used is correct,” they said.
First, they compared a simple, non-thermal PV module to a coated and uncoated PVT unit. In this case, the PV panel has achieved an output of 50.35 W, an electrical efficiency of 9.8%, and a temperature of 75 C at its rear side. The coated PVT module has yielded an output of 53.7 W with an efficiency of 11.2%, with rear temperatures of 42.3 C. The uncoated unit registered 59.2 W, 11.2%, and 41.2 C, respectively.
“When a glass cover is added to the PVT collector, it makes it more efficient at heating,” they added. “However, when the PVT collector does not have a cover, the photovoltaic module cools down better and is more efficient at producing electricity than the regular photovoltaic module and PVT collector.”
When they compared all eight PVT modules with the different configurations, they found the one with round parallel tubes and a glass cover to have the best total efficiency, of 68.90%, followed by covered parallel rectangular tubes with 67%. The lowest performance was of the uncovered parallel round tubes, with 53.43%, while the uncovered spiral tube achieved slightly better results with 54.73%.
The results were presented in “Design and theoretical study of new configuration of photovoltaic/thermal (PVT) solar collector,” published in AIP Advances. It consisted of scientists from Algeria’s University Yahia Fares of Medea and the University of Medea, Saudi Arabia’s King Fahd University of Petroleum and Minerals, Jordan’s Al-Albayt University, Iraq’s Islamic University, Najaf, the Islamic University of Al Diwaniyah, the Islamic University of Babylon, Al-Ayen University, Al-Nisour University College, and Afghanistan’s Kabul University.
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