Photovoltaic (PV) technology is a sustainable solution for energy production, but its performance can be significantly reduced by soiling, especially in humid tropical areas. This study examines the impact of soiling and partial cleaning in stages on polycrystalline PV modules in Casamance (Senegal), in order to optimize their performance in this particular climatic context. The results demonstrate that dust considerably reduces the short-circuit current (Isc), maximum power output (Pmax), and increases module temperature. Progressive cleaning performed on one-quarter of the photovoltaic (PV) module surface leads to a notable improvement in electrical performance, with a significant increase in both current (Isc) and power (Pmax) generated. Over a six-month exposure period from November to May, the dust density accumulated on the photovoltaic modules in 2025 was higher than that recorded during the same period in 2024. Although partial cleaning improves module performance, only complete cleaning achieves optimal results. After complete cleaning, the open-circuit voltage (Voc), short-circuit current (Isc), and maximum power (Pmax) increased by 6.68, 122.97, and 151.46%, respectively. Conversion efficiency rose from 3.5% for an uncleaned module to 8.89% for a fully cleaned module, corresponding to a relative increase of 154%. Furthermore, the temperature of the uncleaned PV module was 17.33% higher than that of the cleaned module during peak solar hours (1:30 p.m.). These findings underscore the importance of implementing appropriate maintenance strategies to preserve the performance and profitability of photovoltaic installations, especially in dust-prone environments.