Comparative and sensitive analysis of the annual performance between the conventional and the heat pipe PV/T systems

The conventional PV/T and the heat pipe PV/T systems have the opposite relative magnitudes of heat loss coefficients during the day-time and night-time. In the present study, their effects on the annual effective supply days, annual heat gain, and annual electric gain are compared and discussed based on the typical meteorological year data of Shanghai city. Influences of setting temperature, photovoltaic coverage ratio, and water tank volume on the operating performance are comparatively and sensitively analysed. The results show that compared with the conventional PV/T system, the lower night-time heat loss of the heat pipe PV/T system distinctly enhances the photothermal performance but modestly weakens the photovoltaic performance. The former increases by 33.20% in annual heat gain while the latter decreases by 6.88% in annual electric gain. Increasing the setting temperature results in a maximum deterioration of 38.79% in annual heat gain but slightly weakens the photovoltaic performance. Increasing the photovoltaic coverage ratio proportionally enhances the photovoltaic performance but evidently weakens the photothermal performance of up to 37.87%. The optimum water tank volume is 60 L. Increasing the water tank volume leads to a maximum decrease of 19.74% in annual heat gain and an increase of 20.25% in heat loss.