In-situ soiling evaluation and cleaning schedules optimization for several PV technologies under desert climate

This study has three objectives. The first one is the measurement and comparison of the soiling impact on three PV technologies: (i) Cadmium telluride (CdTe) (ii) monocrystalline (mono-Si) and (iii) multi-crystalline (m-Si) under a hot desert climate. The second one, is the evaluation of the dust homogeneity distribution on the panels surfaces and how it affects the electrical parameters (Isc and Pmax). As for the third one, we developed several cleaning scenarios to select the optimal one -for each technology and from techno-economical aspects-if installed in desert location. Results show that the Monocrystalline (Mono-Si) is the most affected technology with a daily soiling ratio (SR) reaching 28%, while CdTe is the less affected one with a daily SR of 23.6%. Regarding the soiling distribution, we found that both Isc and Pmax, can be used for the SR assessment in our field of study as they show a good agreement with the power loss (R2 above 98%). Finally, based on the result, a bi-weekly cleaning scenario during the dry period of the year, is the optimal schedule for our site where the energy loss -in comparison to the daily cleaning scenario-is around 3.53%, 3.41%, and 2.27% for the Mono-Si, m-Si and CdTe, respectively. The results of this study may be of high importance for operators and operation and maintenance (O&M) crews working on the PV plants -with similar climate conditions as our field of study-to adjust their cleaning schedules for a better profitability of the power plant and a low water consumption.