The aim of this paper is to review the mathematical models proposed in the literature that evaluate angular losses by means of the incidence angle modifier in photovoltaic modules. The aim of this work is to highlight the importance of considering not only the reflective losses governed by the air-first interface of the photovoltaic module, but also the losses governed by the effect of the accumulation of dust particles on the surface of the modules under real operating conditions, known as soiling. The Martin-Ruiz Model which derives from the mathematical handling of the Fresnel equations and includes analytical solutions for diffuse and reflected irradiance components, is presented as a robust, accurate and reliable analytical model that contemplates these two factors. With the implementation of the Martin-Ruiz Model in SISIFO, a PV simulation software developed by the IES-UPM, optical losses at a 100 MW one-axis tracked PV plant in the Kalahari Desert were simulated. Four different soiling scenarios were considered. The results suggest that the incident angle modifier losses are between 44 to 64% larger than those predicted when considering only the effect of refractive index change. Simulation software integrating models that consider all of these optical losses will improve the energy yield prediction of any photovoltaic plant with more reliable estimations.