CLEANING REGIMES FOR PV MODULES. COMPARISON OF METHODS, COSTS, AND EFFICACY. - Vlad-Mihai, Popescu; Mihai, Cruceru (Annals of 'Constantin Brancusi' University of Targu-Jiu. Engineering Series / Analele Universităţii Constantin Brâncuşi din Târgu-Jiu. Seria Inginerie, 2025)