Prediction of thermal boundary layer thickness and bidirectional effect of dust deposition on the output of photovoltaic modules

Abstract

Photovoltaic power generation was one of the fastest-growing and most promising forms of solar energy utilization, and dust deposition had an important effect on the output capacity of photovoltaic modules. However, the law and mechanism of dust deposition influence the output performance of the PV modules was still not perfect and deep enough at present. In this paper, the prediction model of the thermal boundary layer thickness (δT) was constructed, and the influence laws of dust deposition on the total attenuation rate (rt) of the top surface and the average temperature (TW) of the backplane surface were explored. Besides, the bidirectional effect of dust deposition on the output performance was researched. The results show that the main components of the dust on the top surface of the PV modules were the quartz or aluminosilicate transported remotely by atmospheric circulation and deposited. The δT at any position of the photovoltaic module decreased with the increase of parallel wind speed (v∥) by the law of −0.49800 power function, and convective heat transfer coefficient (h) changed positively with Re by the law of 0.48752 power function. In the total solar irradiance (G) decreases period and dust deposition amount (A) was 2.024201 g/m2, the influence rate of dust deposition (r) had a maximum value of 0.015363. The dust deposition attenuation rate (rdA) and the temperature gain rate (rtE) all changed positively with A by power function law, and the increase rate of rtE and rdA eventually tends to 0 and infinity, respectively. The theoretical dust removal point of the rooftop PV modules in Hohhot Urban was 5.82661 g/m2.