Real-Time Experimental Performance Assessment of a Photovoltaic Thermal System Cascaded With Flat Plate and Heat Pipe Evacuated Tube Collector

In response to the global quest for a sustainable and environmentally friendly source of energy, most scientists’ discretion is solar energy, especially solar thermal. However, successful deployment of solar thermal technologies such as solar-assisted process heating (SAPH) systems in medium- to large-scale industries is still in quandary due to their inefficacy in raising ample temperatures. Cascaded SAPH system, which is essentially a series combination of two same or different types of thermal collectors, may provide a worthwhile solution to this problem. In this article, performance assessment and comparison of two cascaded SAPH systems have been presented: photovoltaic thermal (PVT) cascaded with flat-plate collector (PVT-FPC) and PVT coupled with heat pipe evacuated tube collector (PVT-HPETC). Simulation models have been presented for individual FPC, HPETC, and PVT as well as PVT cascaded with FPC and HPETC systems in TRNSYS and validated through outdoor experimentation. Both the first and the second laws of thermodynamics have been employed to reveal veritable performance of the systems. Results show that PVT-HPETC delivers better performance with 1625 W thermal energy, 81.59% energy efficiency, and 13.22% exergy efficiency. It cuts 1.37 kg of CO₂ on an hourly basis. Cascaded systems can be effective in sustaining industrial process heat requirements.