Effect of dust concentration, wind speed, and relative humidity on the performance of photovoltaic panels in Tehran

ABSTRACT

Impact of dust concentration and weather conditions – wind speed and relative humidity – on power generation of photovoltaic (PV) panels investigated experimentally in Tehran, Iran, for the period of April 10–September 22, 2018. Two Photovoltaic panels together with data-logging equipment were applied in this experiment. One panel was cleaned every day, while the other was remained unclean after 45 days. A performance ratio called “cleanness index” (CI) which is a temperature-corrected performance ratio of a soiled PV panel to that of a clean one was also used to indicate the dust deposition effect on PV panel performance. The uncertainty range of experimental results was between 5.27% and 5.55%. The results show that cleanness index had positive correlation with wind speed and negative correlations with relative humidity and dust concentration. Thus, in comparison to the clean PV panel, the output-power of the soiled panel reduced, approximately 8–12% per month. Furthermore, in order to numerically predict daily change of cleanness index (ΔCI_Pre), a linear regression model was developed and the outcome revealed that dust concentration had the most impact, with 21.56%.

KEYWORDS:

• Photovoltaic panel
• dust deposition
• weather condition
• performance loss
• cleanness index

Nomenclature

$CI$	=	Cleanness index
$G$	=	Irradiance [kW/m2]
$P$	=	Panel power at a maximum point [kW]
$P{M}_{10}$	=	Averaged particle matter concentration, smaller than 10 µm diameter, measured daily [mg.m−3]
$PR$	=	PV panel performance ratio
RH	=	Averaged relative humidity measured daily
$T$	=	PV panel temperature [°C]
WS	=	Averaged wind speed measured daily [m.s−1]

Greek

${\beta }_{0-3}$	=	Coefficients of linear regression model
δ	=	− 0.515% [°C−1], temperature coefficient that corresponds to installed panels
$\mathrm{\Delta }$	=	Difference operator

Subscripts

DC	=	Direct current
i	=	Minute indicator
n	=	Day indicator
POP	=	Plane of panel
pre	=	Predicted
STC	=	Standard test condition
T_corr	=	Temperature-corrected
T_corr_clean	=	Temperature-corrected for a clean PV panel