# Effect of Wind Direction and Velocity on PV Panels Cooling with Perforated Heat Sinks
## 1 Introduction  
The current global political, economic and energy context is characterized by high demand and consumption of population, instability, uncertainty and rampant inflation, right in the area of resources and energy [1]. Even without taking into account the current context, there is the well-known concept of Overshoot Day which is \"celebrated\" each year. In essence, this day represents the moment when humanity had already used up all of the renewable resources of the current year and unfortunately it takes place earlier and earlier each year. For the current year, this day was on 28 July 2022, meaning that from 29 July onwards, we started consuming additional resources compared to how much the planet could regenerate [2]. In this context, the use of solar-related energy could reduce the vulnerability of the European Community and eliminate the dependence of third-party oil or gas producers. Solar energy and its conversion into electricity by using photovoltaic (PV) panels became a major attraction in order to reduce the dependence on fossil fuels. After commissioning, there is obtained a clean and sustainable form of energy [2, 3]. The photovoltaic systems could represent a stable and competitive area [4], taking into account both the recent actions in Europe [5] and the general tendency on the energy market that have quickly affected the stability of the world countries. The advantages of photovoltaic technology are well documented in literature [6], but the control of the PV panels temperature is also an important challenge that could assure the enhancement of their efficiency [7]. The irreversible effect of heat generation in PV panels cannot be avoided, taking into account that the PV panel is constantly exposed to high levels of solar energy. Taking into account the efficiency of recently photovoltaic panels (of 20-25%), it can be stated that the vast majority of the remaining solar energy absorbed is converted into heat. This phenomenon, corroborated with the temperature-dependent variation of the efficiency of PV panels [7], determines a continuous concern on reducing the operating temperature. The data from literature present a decrease of the PV efficiency with the temperature between \(-0.30\) and \(-0.50\%/^{\circ}\)C [8; 9]. It must be specified that, in contrast to STC (Standard Test Conditions), in normal operation the photovoltaic panels can reach temperatures of 70 \({}^{\circ}\)C or higher [8; 10; 11], at 1000 W/m\({}^{2}\), leading to a significant decrease in their efficiency. It is well known that, when it is possible, it is recommended to use cooling solutions for improving PV panels' efficiency and develop PVT panels (photovoltaic-thermal) as a consequence [12; 13; 14; 15]. There are considerable research studies in the literature regarding the cooling solutions for improving the efficiency of photovoltaic panels by reducing their operating temperature [6; 9; 10; 13; 14; 15]. The air-cooling effect using heat sinks is tested for different areas: residential sector, urban and power plants [16; 17]. The aim of this study was to analyze the effect of wind direction and velocity over different types of heat sinks attached to PV panels in comparison to the base case (without a cooling solution). The main target of the work was to quantify the cooling effect of various heat sinks in variable wind conditions. The presence of heat sinks is influencing the performance of PV panels, but the wind directions could also be an important factor in this regard. In contrast to the majority of similar studies in the literature, in this paper, the numerical modeling was conducted in more realistic wind conditions and inclination of the PV panel [18].