Numerical study of the cooling effect of a PVT on its thermal and electrical efficiency using a Cu tube of different diameters and lengths

The modeling of the cooling of solar panels (SP) using a copper tube is done in this article. The SP is 60 W with dimensions of 68 × 70 cm. The effective variables include the diameter of tubes in three standard sizes of 9.53, 12.70 and 15.88 mm, the number of used 180° elbows (number of loops), and the flow rate in the range of 0.5 to 2.5 lit/min. solar radiation equations are also considered and the finite element method (FEM) is used in COMSOL Multiphysics software. Finally, optimization is done to obtain the best-operating conditions of the SP. The results showed that the highest electrical efficiency (EE) with a value of 14.8% occurs at a flow rate of 2.5 lit/min for a tube diameter of 9.53 and presence of 11 loops. The highest thermal efficiency (TE) and overall efficiency (OE) are 79.1% and 92%, respectively, which occur at a flow rate of 1.5 lit/min for 11 loops of 15.88 mm copper tubes. The best conditions for having the lowest SP temperature, the lowest pressure drop and the highest outlet temperature of the SP occur at a flow rate of 0.68 lit/min for a pipe diameter of 15.88 mm and a number of loops of 11.