A comparative analysis of energy and exergy performance of different PVT collector configurations

Photovoltaic thermal (PVT) collectors have emerged as promising hybrid systems capable of simultaneously generating both electrical and thermal energy from solar radiation. Compared to standalone photovoltaic panels or thermal collectors, PVT systems offer higher energy efficiency per unit area and improved cost-effectiveness, while also reducing PV cell temperature-related efficiency losses. However, the performance of PVT collectors is highly sensitive to a range of design and operational parameters, including absorber geometry, flow configurations, and inlet-outlet arrangements. This study presents a comprehensive numerical investigation of 47 different PVT collector configurations derived from 26 absorber designs, categorized into three main groups: parallel, serpentine and spiral tube geometries. All configurations were modeled in 3-D using COMSOL Multiphysics software based on the finite element method, under steady-state, laminar, and incompressible flow assumptions, and a total of 1615 simulations were performed, each requiring approximately two hours of computational time on the workstation. Each design was standardized to ensure equal absorber surface areas and tube lengths, enabling fair comparison across all configurations. A detailed performance analysis was conducted using a combination of energy and exergy-based metrics such as thermal and electrical power output, overall and primary energy saving efficiency, pressure drop, thermal energy per unit pressure drop (TEPD), and exergy efficiency. Additionally, the effects of key operating parameters including fluid flow rate, solar irradiance, fluid inlet temperature, ambient temperature, and wind velocity were systematically examined. Among all configurations, the highest thermal energy output was achieved by the parallel tube design coded as Config E (949.83 W), while the serpentine tube Config R1 delivered the highest electrical output (255.95 W) and exergetic performance. Config E demonstrated the highest overall (0.7564) and primary energy saving efficiency (0.9941), while parallel tube Config F achieved the top TEPD value of 74.91 W/Pa at 5 L/h flow rate. Config R1 recorded the maximum exergy efficiency with 0.1498, followed by serpentine tube Config H at 0.1496 and Config E at 0.1494.