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Investigation of PV soiling and condensation in desert environments via outdoor microscopy

Abstract : Soiling of photovoltaic (PV) modules greatly degrades their performance in desert environments. Previous field studies have tended to find weak correlations between the soiling rate and weather parameters. It was thought that one reason was the long measurement interval — days or weeks — of conventional field soiling measurement techniques. In the present study, an “outdoor soiling microscope” (OSM) was developed able to measure deposition and detachment of individual dust particles, every 10 minutes, in outdoor conditions, day and night. By using a greased and ungreased pair of OSMs, it was further possible to separate soiling into three component dust flux rates — deposition, immediate rebound, and delayed resuspension. OSMs were used to measure flux rates in field experiments in Doha, Qatar. The novel method revealed explanatory effects of environmental parameters that had previously been obscured by limits of conventional long soiling measurement intervals and confounded dust flux rates. The OSM could also measure the onset and growth of microscopic condensation droplets in field and laboratory settings. Such experiments, along with isotherm measurements and composition analysis, demonstrated that condensation on soiled surfaces at the test site was strongly influenced by the presence of hygroscopic matter in the dust other than NaCl. Because of such matter, microscopic condensation could persist on both hydrophilic and hydrophobic surfaces well above the dew-point temperature. Results of the study suggest that soiling of PV modules might be mitigated by taking advantage of natural time-of-day variations in weather conditions.
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Submitted on : Monday, July 2, 2018 - 6:19:06 PM
Last modification on : Tuesday, January 22, 2019 - 3:08:22 AM
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  • HAL Id : tel-01827881, version 1


Benjamin Figgis. Investigation of PV soiling and condensation in desert environments via outdoor microscopy. Mechanics of materials [physics.class-ph]. Université de Strasbourg, 2018. English. ⟨NNT : 2018STRAD006⟩. ⟨tel-01827881⟩



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