## 1 Introduction  
One of the important challenges in operating and maintaining photovoltaic (PV) systems on a worldwide basis is to avoid soiling on a PV module surface as far as possible in order to prevent a decrease in performance. This effect results in serious losses in energy generation, thus affecting PV project viability. Cleaning costs may considerably increase the price of the energy generated since it depends on the type of cleaning (manual or robotic), the use of water (dry cleaning), and cleaning frequency (daily, weekly, monthly, semestral or annual) [1, 2]. [PERSON] et al. claimed that soiling is a highly important issue that must be considered in the solar market since, in an optimum cleaning scenario, soiling may reduce solar energy production by 3-4%, being equivalent to economic losses of at least 63-5 billion annually on a worldwide basis, without considering monetary losses due to the selection of inappropriate and scarcely efficient cleaning techniques [2]. In addition, the current scenario produced by the COVID-19 pandemic and the monetary instability on a worldwide basis have led to a situation that fosters the development and innovation of efficient cleaning plans and techniques to optimize the economic resources of a PV plant and to ensure profitability [3]. For these reasons, researchers around the world are seeking different ways to simplify soiling studies via outdoor and indoor experimental campaigns and computing simulations to provide efficient solutions suitable for the present panorama [4; 5; 6; 7].  
Defining a maintenance plan that is adequate for each PV plant to minimize optic and economic losses is a complex task, owing to the different factors related to soiling deposition. These factors are grouped as: Climatic conditions (wind speed and direction, relative humidity, ambient temperature, solar radiation, airborne dust, and precipitations), type of soiling (inorganic and organic), installation factors (slope and orientation), and type of technology (modules and glass) [8; 9]. These factors are further divided into other subsections, making soiling research more complex. For instance, to study the nature of soiling, it is necessary to understand the type of material deposited, its size, morphology, chemical composition, load, and solubility. If the soiling interaction with the panel is added to this, other variables, such as capillarity, must be considered, e.g., capillarity, Van der Waals and Coulomb forces, mechanical interlocking, and contact electrification [10; 11]. However, soiling studies show an additional complexity, since soiling is considered as a local phenomenon. Every area around the world has unique characteristics that interact differently with the PV module, such as the combination of compounds deposited, precipitation level, solar resource quality, wind speed and direction, airborne dust, and relative humidity, thus making many studies unreproducible for PV installations on a worldwide basis [12; 13; 14].  
This study shows how local soiling studies can be conducted to decrease the number of variables to be analyzed, thus obtaining highly reliable results. Attention is focused on PV module soiling deposition, which is analyzed from its physicochemical nature and the influence of geology on the site. In addition, soiling effects on the optical properties of a PV glass installed with a fixed slope configuration is evaluated by analyzing IV current-voltage curves. This results in a methodology for improving soiling cleaning and mitigation plans for PV plants, thus directly affecting PV Project profitability for investment (CAPEX) and maintenance operation (OPEX).