Experimental and Theoretical Modelling of Concentrating Photovoltaic Thermal System with Ge-Based Multi-Junction Solar Cells

Abstract

Climate change is one of the biggest environmental, political, economic, technological, and social challenges of the 21st century. Due to ever-increasing fossil fuels costs. The world energy system should be transitioned to renewable energy sources to mitigate greenhouse gas emissions. Solar energy is one of the suitable alternatives to fossil fuel usage. Currently, the most widely available solar technologies are solar photovoltaic (PV) and solar thermal. The integration of these two techniques enables the exploitation of the most significant amount of solar radiation. This combination has led to a hybrid photovoltaic/thermal system (PV/T). Concentrated solar radiation on PV cells, known as concentrated photovoltaic (CPV), effectively decreases PV receivers’ area and harnesses the same quantity of solar radiation. However, the main problem with CPV is the elevated PV surface temperature, which often requires active cooling. This issue can be solved by introducing a Concentrating Photovoltaic Thermal (CPVT) system. In this article, a new CPVT hybrid system based on Point Focus Fresnel Lens (PFFL) and embedded Multi Junction Photovoltaic (MJPV) (GaInP/InGaAs/Ge) cells has been experimentally investigated and numerically modelled under indoor conditions. Experiments and simulations were carried out at different heat transfer fluid (HTF) flow rates and under constant irradiation emitted from a sun simulator. The results indicate that the thermal and electrical performance of the CPVT system improves under the testing conditions, where the total efficiency was 68.7% and 73.5% for the experimental and CFD models, respectively. At the same time, the highest thermal efficiency of the experimental and CFD models was 49.5% and 55.4%, respectively. In contrast, the highest electrical efficiency was 36.5% and 37.1%. Therefore, the CPVT system has an excellent possibility of being competitive with conventional power generation systems.

A Numerical Investigation of the Feasibility of a Concentrating Photovoltaic Thermal System based on Point-Focus Fresnel Lens

“…The objective of CFD model validation is to verify the accuracy and reliability of the CPVT model results. The designed CPVT model was compared with the experimental results at the same number of cells, geometry dimensions, material properties, and operating and boundary conditions [16]. Cell temperature is a significant parameter.…”

“…There are three kinds of heat transfer mechanisms: convection, conduction, and radiation. Some of this heat is transferred within the MJPV solid layers by conduction, with the remaining parts of the heat lost to the surrounding environment by convection and radiation [16]. The maximum concentration ratio of the CPVT system is calculated as follows [17]:…”

Assessment of Concentrated Photovoltaic Thermal (CPVT) Systems Using CFD Analysis

“…CFD model validation aims to verify the accuracy and reliability of the CPVT model results. The proposed CPVT model was compared with the experimental results conducted by Hmouda et al [25] at the same number of cells, geometry dimensions, material properties, and operating and boundary conditions. Cell temperature is a significant parameter.…”

“…Hmouda et al [25] have designed a new CPVT hybrid system based on a point-focus Fresnel lens and embedded multi-junction photovoltaic cells. Their proposed model was experimentally investigated and numerically modelled under indoor conditions.…”

Indoor Experimental Analysis of Serpentine-Based Cooling Scheme for High Concentration Photovoltaic Thermal Systems

“…Removal of broad assumptions leads to more realistic performance indicators, particularly lower efficiency values. Studies with theoretical focus need to use experimental data for validation to ensure accuracy, preferably this will be specific to the experimental set up as in [19][20][21]. When this is not possible, several studies use literature data to validate the model when set to the same boundary conditions ( [22,23]), although this adds less certainty.…”