Performance characteristics of optimized bi-fluid photovoltaic-thermal solar system: A comparative study of innovative cooling system made of different materials

Abstract

High ambient temperatures reduce the efficiency and lifespan of PV solar systems due to cell overheating. Solar PV cooling can prevent this and improve performance, especially in hot regions. This work attempts to develop a novel, economic, and efficient bi-fluid cooling technology to reduce temperature rise and enhance the overall energy output of hybrid PVT systems. The proposed bi-fluid cooling system involves the use of an absorber plate integrated with a locally available wire-on-tube (serpentine-shaped tube) heat exchanger mounted on the back side of the PVT system for cooling water flow. The heat exchanger is also equipped with air passages for air circulation and natural convection cooling. This type of heat exchanger, which uses bi-fluid cooling technique, can significantly enhance the heat dissipation generated by the solar PV cells, improving the overall performance of the system. Three identical cooling systems made of copper (PVT-Cu), aluminum (PVT-Al), and stainless steel (PVT-Steel) were proposed, studied, and compared to achieve optimal system performance. A life cycle cost analysis (LCCA) was also performed, and the data obtained were compared with those of a conventional PV-standard system to evaluate the feasibility and annual performance of the systems. The developed 3D numerical model of the PVT systems integrated with the proposed bi-fluid cooling systems was simulated using Ansys Fluent 2024. The developed numerical model was also validated with experimental data from the previous study. Results showed that the improvement in the average surface temperatures of the proposed PVT-Steel, PVT-Al and PVT-Cu systems was 1.62, 2.61, and 5.27 %. The average daily increase in electrical output of the proposed PVT-Steel, PVT-Al, and PVT-Cu systems was 7.66 %, 13.51 %, and 16.04 % higher. The improvement in electrical efficiency when using the proposed PVT-Steel, PVT-Al, and PVT-Cu systems was approximately 9.14 %, 15.20 %, and 17.93 %, respectively. The lowest levelized cost of energy (LCOE) was achieved by the proposed PVT-Cu system at $0.47 per kWh, followed by PVT-Al ($0.49 per kWh), and finally with PVT-Steel ($0.52 per kWh). The payback time of the three proposed PVT-Cu, PVT-Al, and PVT-Steel systems was reduced by 78.78 %, 59.96 %, and 40.89 %, respectively.