**1. Introduction**

The production of electricity from solar PV has become an increasingly crucial source of energy [1], conversion of solar energy into electricity is required by means of solar PV cells. These photovoltaic cells are usually made from silicon, which remains the most technologically and industrially advanced field [2]. Among the environmental factors that can have a detrimental impact on the performance of PV cells is dust accumulation.

Dust accumulation on PV modules affects solar PV plants worldwide. In fact, the dirt deposited on the surface of the PV panels consists of mineral dust, aerosols, pollen, fungi and/or other contaminants [3]. The dust particles absorb, disperse, and reflect a proportion of the incident sunlight, thus reducing the intensity of light reaching the active part of the PV cell. Therefore, in some regions, a power degradation of more than 50% has been reported in the literature [3, 4].

Determining the physical properties of dust (e.g., size, geometry, weight, and type of pollutant) provides information's on the degradation of PV module performances

[5]. It is important to understand the relationship between the dust amount and its impact on the dispersion and transmission of sunlight. Several authors found that the accumulated dust on solar panel are dominated by the region [6]. In the literature, the authors [7] discern that the presence of dust on the surface of PV modules reduces their power by half if they are exposed for 6 months without cleaning. The dust accumulation process is directly related to the wind movement; depending on its strength and speed, it gradually covers the entire surface of the PV panel with several thin layers of dust [7, 8]. On the other hand, in southern Spain, a study of [8] reported that the daily energy losses due to dust were about 5% for 12 months, but in Cyprus, the authors [9] estimated a 13% power output decrease due to dust recorded during 12 months of data recording.

The degradation of the efficiency of solar panels is mainly due to the decrease in optical transmittance due to the accumulation of dust on the upper part of the PV panel's [10]. The dust accumulation process is directly related to the wind movement; depending on its strength and speed, it gradually covers the entire surface of the PV panel with several thin layers of dust [7, 8, 11].

In this chapter, an electro-optical investigation of the dust accumulated on the PV panel in the study area of Agadir-Morocco has been presented, by using a MOSFET transistor as load to truck the IV and PV characteristics of SX330J. The experimental results was compared to the simulation, and good agreement was founded.

This chapter is organized as follows: After introduction, in Section 2; we present the study area. Then in Section 3; we give the methodology used in this investigation. Then, we present the electrical modeling and simulation of PV panel under dust in Section 4, the results and discussions in the Section 5. Finally, we conclude our chapter with a conclusion on our investigations, while proposing some perspectives, to further develop this work.
