Numerical simulation and experimental validation of tri-functional photovoltaic/thermal solar collector

Research on PV/T (photovoltaic/thermal) solar collectors has been conducted for years because the collector can provide electric power and thermal energy simultaneously. A tri-functional PV/T collector is presented and studied in this paper. The collector can work in PV/water-heating mode or PV/air-heating mode for different energy demands. For two working modes, steady-state model and dynamic model of the collector are developed and validated with experimental results. Based on the validated models, the performance of collector is investigated under different flow rates, wind speeds, inlet air temperatures, and initial water temperatures. For PV/air-heating mode, the effects of wind speed and flow rate are investigated. A flow rate of 0.02 kg/(m2·s) is recommenced to balance the temperature increase and thermal efficiency. For PV/water-heating mode, the decrease of thermal efficiency with wind speed increase is observed but it slows down when wind speed is over 5 m/s. The curve of daily thermal efficiency is plotted with different initial water temperature in tank. With annual analysis under different climates, the tri-functional PV/T collector is proved to have better annual performance than separated PV/T water collector and PV/T air collector which could be left unused in some seasons.