Influence of Thermal Storage Tank Sizing on the Performance of Photovoltaic-Thermal Systems
Abstract
A thermal storage tank (TST) plays a key role in photovoltaic-thermal (PVT) systems, being responsible for storing heated water from PVT modules and improving the delivery of hot water to the point of consumption. The present study investigates how TST size affects the performance of a PVT system. Two configurations, each composed of one PVT module, a pump, and a TST with volumes of 300 L and 100 L, were tested under similar solar irradiance conditions. The 100 L TST heated up more rapidly, enhancing thermal efficiency in the early hours of the day; however, the thermal energy accumulation reduced the cooling capacity of the photovoltaic (PV) cells and consequently the electrical efficiency. In contrast, the 300 L TST, due to its higher thermal inertia, maintained more stable temperatures and smaller variations throughout the day, keeping the cells at lower temperatures and resulting in higher electrical efficiencies. These results highlight the dynamic behavior of the system, in which thermal and electrical efficiencies vary throughout the day according to the TST volume. The findings emphasize the importance of proper sizing of the TST volume to balance electrical and thermal energy outputs and provide experimental evidence to support future optimization of PVT systems for different demand profiles.
Keywords
PVT system, thermal storage tank, tank sizing, thermal efficiency, water tank temperature