{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T11:00:11Z","timestamp":1773918011942,"version":"3.50.1"},"reference-count":26,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2018,1,26]],"date-time":"2018-01-26T00:00:00Z","timestamp":1516924800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Energies"],"abstract":"<jats:p>Soiling is a problem for solar energy harvesting technologies, such as in photovoltaic modules technologies. This paper describes not only one complete year of Soiling Ratioindex and rates measured in a rural environment of Southern Europe, but also focuses on the seasonal variation of the type of soiling, mainly spring and summer. The Soiling Ratio index is calculated based on the maximum power output and short circuit current of two photovoltaic (PV) panels, along with Scanning Electron Microscopy and Energy Dispersive X-Ray of glass samples to provide visual and chemical inspection of the type of soiling. Mass accumulation on glass samples mounted on a \u201cglass tree\u201d was weekly measured with a microbalance and related with the Soiling Ratio metrics. Soiling rates were calculated to infer the degree of soiling for each season and the respective comparison made. Results show a soiling rate of 4.1%\/month in April (spring), 1.9%\/month in July (summer) and 1.6%\/month in September (fall). Rain (the main natural cleaning agent of the photovoltaic modules) as well as aerosol optical depth (proxy for atmospheric particle concentration) were correlated with the Soiling Ratio. In-depth analysis on the type of organic soiling was performed.<\/jats:p>","DOI":"10.3390\/en11020294","type":"journal-article","created":{"date-parts":[[2018,1,26]],"date-time":"2018-01-26T03:08:06Z","timestamp":1516936086000},"page":"294","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":43,"title":["Organic Soiling: The Role of Pollen in PV Module Performance Degradation"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7341-7611","authenticated-orcid":false,"given":"Ricardo","family":"Concei\u00e7\u00e3o","sequence":"first","affiliation":[{"name":"Renewable Energies Chair, University of Evora, 7002-554 Evora, Portugal"},{"name":"Institute of Earth Sciences, University of Evora, 7000-671 Evora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6838-4827","authenticated-orcid":false,"given":"Hugo","family":"Silva","sequence":"additional","affiliation":[{"name":"Renewable Energies Chair, University of Evora, 7002-554 Evora, Portugal"},{"name":"Institute of Earth Sciences, University of Evora, 7000-671 Evora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0103-3448","authenticated-orcid":false,"given":"Jos\u00e9","family":"Mir\u00e3o","sequence":"additional","affiliation":[{"name":"Hercules Laboratory, University of Evora, 7000-089 Evora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0717-9819","authenticated-orcid":false,"given":"Manuel","family":"Collares-Pereira","sequence":"additional","affiliation":[{"name":"Renewable Energies Chair, University of Evora, 7002-554 Evora, Portugal"},{"name":"Institute of Earth Sciences, University of Evora, 7000-671 Evora, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2018,1,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1016\/0038-092X(74)90019-X","article-title":"Effect of dirt on transparent covers in flat-plate solar energy collectors","volume":"15","author":"Garg","year":"1974","journal-title":"Sol. 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