## 3 Data Collection and Preprocessing
### Description of Data Sources
#### 3.1.2 Local Weather Parameters  
Other meteorological data that could not be obtained from the meteorological station of the PV power plant in question were obtained from source [79]. Unlike the data taken from the PV station, these data are not obtained from the point where the power plant is located. They are obtained from general measurements of the region where the power plant is located. These data include temperature, relative humidity, and dew point measurements two meters above sea level. Wind speed and direction were measured at 10 m and 80 m above ground level. The wind gust value was measured at 10 m. Visibility, precipitation, and apparent temperature are also among these data. Radiation is categorized into four types: shortwave, direct, diffuse, and terrestrial. Direct normal irradiance, with its instantaneous value, and finally global tilted irradiance instant are other local data used. As the relative humidity increases, dew can form on the surface of PV modules. Dew droplets will reflect incoming solar radiation in different directions, reducing the amount of incoming energy. This is a negative effect of relative humidity; however, it can have a positive impact on power generation, as the evaporation of dew can provide additional cooling to the PV modules [85]. Another local datum used in the study is the dew point. If a humid air mass is cooled at constant pressure, it reaches saturation, and liquid water  
Figure 3: Influence of irradiance on I–V curve [84]. Figure 2: Influence of temperature on I–V curve [84]. forms in the form of dew or fog. The temperature at which this occurs is defined as the dew point of the air [86]. In PV studies, precipitation is generally considered to be the accumulation of water in the form of wetness. Precipitation reduces temperature, especially in spring and summer, cleans the surface of dust, and can reduce reflection losses in cases where a thin water layer forms. With these features, its contribution to power generation can be considered positive. Its effect in autumn and winter is not fully evident [87,88]. Visibility measures the distance at which an object or light can be clearly distinguished. This parameter affects the efficiency of PV modules due to the negative effects of light absorption and scattering by gases, water vapor, and dust particles in the air [89]. Large fluctuations in atmospheric winds at small scales are defined as wind gusts [90]. This parameter is also among the data considered in the study. Wind direction is a frequently used data point, along with wind speed, in PV forecasting studies. The effect of wind direction on PV power generation varies depending on the hemisphere in which the plant is located. A PV plant in the northern hemisphere positively affects production when it receives strong and frequent winds from the south. A PV plant in the southern hemisphere benefits from its performance when it receives strong and frequent winds from the north [91]. Local parameters related to the sun are as follows:  
Shortwave radiation is the total solar radiation with wavelengths ranging from 300 to 3000 nm [92]. Sunlight that is not scattered is called direct beam radiation. Direct beam, when sunlight illuminates a plane perpendicular to the direction of the sun, is referred to as direct normal radiation. Therefore, any shortwave radiation consists of two basic components: direct and diffuse. Direct and diffuse radiation are collectively referred to as global radiation [93]. Global tilted irradiance expresses the total solar energy received per unit area of a sloped surface. It includes direct radiation and diffuse components. It provides an approximate value for calculating the energy yield of PV panels positioned permanently at a certain inclination [94]. The longwave, low-energy radiation that the Earth emits, corresponding to the emission spectrum of a mixture of blackbody spectra with temperatures ranging from 220 to 320 K, is called terrestrial radiation.