Economic evaluation and annual performance analysis of a novel series-coupled PV/T and solar TC with solar direct expansion heat pump system: An experimental and numerical study

Abstract

Hybrid photovoltaic/thermal (PV/T) systems are proposed to harvest the two renewable forms of energy, thermal and electrical. The PV/T system generates low-temperature thermal and electrical energy, which is usually not much and might meet the demand for residential building heating and hot water. This research presents the economic evaluation and annual energy performance of a novel series-coupled PV/T and a solar thermal collector (TC) with a solar direct expansion heat pump system. A comprehensive approach was developed and utilized to evaluate the quantitative and qualitative performance of the hybrid refrigerant-based PV/T-TC system using the 1st (energy) and 2nd (exergy) laws of thermodynamics. A 0.5234 kW rating heat pump prototype system with a PV/T-TC area of 3.5 m2 was built and tested under the real conditions of Karachi, Pakistan, and a simulation model was developed via MATLAB to predict the annual energy performance. The experimental results show that the PV/T-TC system's mean daily electrical, thermal, overall energy and exergy efficiencies were 14.08%, 60.12%, 74.20%, and 18.12%, respectively. The numerical results reveal that a PV/T-TC assisted solar heat pump system can generate 303.51 kWh of electricity and 3213.12 kWh of thermal energy annually. The annual average COP of the hybrid refrigerant-based PV/T-TC system is 5.68. According to the comparison of economic performance between the PV/T assisted direct-expansion heat pump system and PV/T-TC assisted direct-expansion heat pump system, the hybrid refrigerant-based PV/T-TC assisted direct-expansion heat pump system has a payback period of 5.20 years, whereas the refrigerant-based PV/T assisted direct-expansion heat pump system has a payback period of 7.15 years. The experimental data is consistent with the simulation outcomes, with an average relative error of 3.30%.