Experimental analysis and modeling of weather condition effects on photovoltaic systems’ performance: Tehran case study

ABSTRACT

Increased reliability in grid-independent photovoltaic systems is an important factor in the prevalence and greater use of solar systems. The present study was conducted in Iran. It is one of the countries with high potential in the field of solar energy with average radiation of 5–5.5 kWh/m² intensity. On the other hand, due to the wide desert areas, it is important to investigate the effect of dust deposition on photovoltaic panels. An experimental study on the performance of photovoltaic panels over a 90-day period from May 25 to August 22, 2018, in Tehran, and under real conditions, to investigate the effect of dust deposition and climate change on their output power was performed. Because of its large population, political and economic conditions, Tehran has the highest importance amongst other cities in Iran. The results showed that the dirty panels produced 10% less power than the clean panels. Utilization of the data achieved from the experiment, the output power of the clean and dirty panels considering the air temperature and solar radiation is modeled using the MLR method. In order to establish the relationship between the reductions of the output power of the panel, due to the deposition of walnut dust, the soiling ratio (SR) is used. This ratio is gained by dividing the output power of the dirty panel by the output power of the clean panel to obtain a coefficient to determine the reduction of the output power of the desired photovoltaic panel in terms of air temperature and solar radiation. The coefficient earned with the correlation coefficient of 0.9 (R²) and the error of the mean root squares 7.94 (RMSE) can well predict the loss of power output of the panel due to dust sediment on the surface of the panel. The uncertainty range of experimental results is between of 7.83% to 8.08%.

KEYWORDS:

• Photovoltaic Systems
• dust deposition
• multi-variable regression
• ambient air temperature
• soiling ratio

Nomenclature

A	=	PV panel surface area (m2)
$a$CL	=	Regression coefficients Cable Loss
X	=	independent variable matrix
E	=	Solar radiation intensity (W/m2)
E	=	Fitting error
k	=	number of independent regresses
$\stackrel{\prime }{X}$	=	inverse matrix of X
PM10	=	Averaged particle matter concentration, smaller than 10 µm diameter, measured daily [$\mathrm{m}\mathrm{g}/{\mathrm{m}}^3$]
P	=	Daily output power
RH	=	Averaged relative humidity measured daily
Z	=	dependent variables’ vector
WS	=	Averaged wind speed measured daily [m/s]
SR	=	soiling ratio
R2	=	Coefficient of Correlation
U	=	Uncertainty
T	=	Temperature
RM	=	Radiation Meter [W/m2]
Th	=	Thermometer [°C]
Greek	=
$\beta$	=	Regression coefficient vector
$\epsilon$	=	Fitting error vector
$\eta$	=	Panel’s efficiency
Subscripts	=
I	=	Numerator
R	=	random error
N	=	number of points in your data
F	=	fixed error

Additional information

Notes on contributors

Hossein Salimi

Hossein Salimi was born in Tehran on1962. He received the B.S degree in mechanical engineering from Iran University of science and technology, Iran and the M.S degree in mechanical engineering from Islamic Azad University, South Tehran Branch, Iran and the PhD degree in Energy Systems engineering from Islamic Azad University, South Tehran Branch. He is currently an Assistant Professor of Mechanical Engineering Department at Islamic Azad University South Tehran Branch.

Hossein Ahmadi Danesh Ashtiani

Hossein Ahmadi Danesh Ashtiani was born in 1971. He is graduated in mechanical engineering and got his Ph.D. degree in Energy Engineering in 2004. His interested fields are Energy saving, Pinch Technology, exergy analysis fossil fuels, and renewable energies and he has some related papers in English and Persian language. He is a member of staff and head of mechanical and energy engineering at Islamic Azad University, South Tehran Branch.

Arash Mirabdolah Lavasani

Arash Mirabdolah Lavasani was born in Tehran on1971. He received the B.S degree in mechanical engineering from Khajeh Nasir Toosi University of Technology, Iran and the M.S degree in mechanical engineering from Shahid Bahonar University of Kerman, Iran and the PhD degree in mechanical engineering from Islamic Azad University, Science and Research Branch. He is currently an Associate Professor of Mechanical Engineering Department at Islamic Azad University Central Tehran Branch.

Reza Fazaeli

Reza Fazaeli was born in Tehran on1972. He received his PhD degree in physic and chemistry in 2001. He is currently an Assistant Professor of Chemical Engineering Department at Islamic Azad University South Tehran Branch.